Transmission of reference signals often requires a high level of phase stability. Optical fibers are generally the transmission medium of choice. This paper examines the effect of ASE noise on the phase of reference signals.

A new type of optical instrument, the curved hologram, is introduced that allows us the unique opportunity to independently control its spatial phase function and its shape. We show how proper design of the hologram shape (using a simple analytic procedure) yields perfect uniform collimation, and also collimation and concentration of diffuse (monochromatic) light at the thermodynamic limit of brightness conservation.

Films of various squarilium (Sq) derivatives were deposited using thermal evaporation (TE), laser beam evaporation (LBE) and plasma treatment in vacuum. A row of indolenine derivatives of Sq with various side and end groups was studied. Films had different band positions in absorption spectra that dependent on Sq structure. One absorption band in a solution was split into two peaks for the film. Dyes were deposited onto oriented polytetrafluoroethylene (PTFE) sublayers. Aligned PTFE sublayers were prepared by friction-transfer method and evaporation with consequent rubbing by a cloth. Two Sq compounds revealed oriented growth on PTFE sublayer. Thickness - dependent change in the relative intensity of shorter and longer wavelength peaks was found. Some other vacuum-deposited polymers revealed the ability to orient Sq dye after rubbing.

Dye-filled polymer nanocomposite thin films are of great interest due to their unique electronic and optical properties. They are perspective for applications in luminescent, nonlinear, solar energy conversion and other optoelectronic devices. Recently polymer films filled with dye by evaporation in vacuum became a subject of growing interest. Simultaneous evaporation from two sources allows to deposit a film with any ratio between components. Dye+polymer films are deposited using co-evaporation of the compounds in vacuum, pyrolysis+evaporation, laser evaporation of composite target. Several polymers, such as polytetrafluoroethylene (PTFE), polychlorotrifluoroethylene (PCTFE), polystyrene (PS), polyparaphenylenesulphide(PPS), polyparaxylylene (PPX) were filled with dye molecules. Several dyes of various kinds were used for co-deposition. Polymer matrix prevents aggregation even during annealing, enhances film stability and endurance. Combined co-deposition methods give powerful tool for film optical properties controlled design. They allow to control independently nanoparticles concentration and material structure both for matrix and filler, which is resulted in optical properties of the film.

General backgrounds as well as experimental results for polymer, dye and composite film deposition by thermal and laser evaporation, plasma enhanced chemical vapour deposition and combined methods are presented. Nonlinear and electroluminescent properties of the such films are discussed.

Remote optical techniques are well suited for obtaining representative average values for gas fluxes emanating from a semi-infinite flat surface. Unisearch, the Alberta Reserach Council and the University of Alberta have developed a technique and methodology for making such measurements using a near-IR tunable diode laser analyzer and a set of open path optics. The technqiue uses the LasIR to measure gas concentrations at two different heights along paths which folow the perimeter of a square, flat surface. The measurements are used to calculate a concentration gradient across the height difference. These values, along with air temperature, relative humidity, soil heat flux, net radiation and wind speed/direction data, are then used to calculate the average flux emanating from the surface by applying an integrated flux gradient analysis based on Monin-Obukhov similarity theory. This method was applied to measure fluxes of methane emanating from a 50m × 50m test agricultural plot after the application of manure. Plans are underway to extend the capability of the system to measure up to four different species simultaneously.

The moire interferometry has been used to investigate the strains induced by thermal loading in various electronics packages. The AFM scanning moire technique has also been utilized to measure the strains of electronics packages with an even better resolution. The advantages and disadvantages of the full field moire, the micro moire, and the AFM scanning moire techniques are compared.

This paper discusses surface texture characterization of silicon, silicon carbide and some metal surfaces using a Chroma Meter. The specimen surfaces were obtained with various machining methods. Lightness (brightness) has a good correlation with surface roughness and could be used as an in-process/in-cycle/post-process technique for surface texture characterization. Surfaces with lower roughness values had lower lightness values.

The common approach to designing multimode fiber coupling lenses is based on fiber end-face imaging. A model, proposed here, deals with beam profiles. Paraxial ray tracing shows that the output of a graded-index multimode fiber has a hyperbolic profile, similar to a singlemode beam. Focusing this beam by a lens is similar to a Gaussian beam focusing. Light focused from a step-index multimode fiber has two waists. Matching their size and NA to fiber parameters is not enough for good coupling: the beam profile should in fact be corrected. The propagation properties of graded-index multimode fiber beams are similar to singlemode beams and differ from step-index multimode fiber beams. The beam profile approach defines these properties, while the imaging approach often fails. A ray model, describing the beam profile, is convenient in computer simulation of lens systems for fiber optics. It visualizes beams in ray-tracing codes such as ZEMAX and allows aberration optimization regarding minimal beam distortion. Gaussian beam diffraction is not an issue, if there is no beam clipping - the ray model is consistent with the traditional wave model. These results are important for correct design of fiber coupling lenses.

A light beam coming from a heterodyne light source and is divided into three parts by two beam-splitters. Two parts are guided to be incident on the thin metal film on a surface plasma resonance (SPR) probe from two other sides. Two groups of multiple reflected beams occur in the thin metal film, they pass through their corresponding analyzer and lens, and are detected by the associated photodetectors. So we have two test signals. On the other hand, the other part passes through an analyzer and enters a photodetector. The intensity measured by the photodetector is the reference signal. These two test signals and the reference signal are send to a phse meter, the phase differences between the test signals and the reference signal can be obtained. Substituting these data into the special equations derived from Fresnel's equations and the principle of multiple beam interference, the complex refractive index and the thickness of the thin metal film of the probe can be estimated. Because of its common path optical configuration and its heterodyne interferometric phase measurement, this method has many merits, such as, high stable against the surrounding vibration, high resolution, real time operation. In addition, four samples are tested to show the validity of this method.

A novel polarization mode dispersion (PMD) emulator is presented which accurately follows the dynamics of PMD in field optical fiber. A modification on a dynamic mode coupling wave-plate model is presented to model the emulator. It is found that the emulator and model can accurately describe the dynamical behaviour of the state of polarization (SOP) and thus PMD in a fiber.

We have investigated the writing of waveguides in pure fused silica glass with femtosecond Ti:sapphire laser at 1 kHz repetition rate. The obtained results were compared for two writing configurations with pulse durations of 200 fs and 45 fs, and with different exposure energies and translation speeds of the sample. The magnitude of the refractive-index changes in the glass was measured as a function of light exposure, where index changes as large as 5×10-3 were achieved.

For the purpose of heterodyne optical phase-locked-loop (OPLL), a compact and efficient frequency stabilization system has been developed using a single reference cavity for simultaneous application of optical feedback along with electrical feedback. Using the identical reference cavity for each feedback technique makes the system compact. The phase margin of optical feedback loop can be maximized by stabilizing the center frequency of a laser diode (LD) to the reference cavity mode, which is identical to the optical injection locking mode based on negative electrical feedback. To improve the long-term frequency stability relative to the reference frequency, the optical feedback path length has also been controlled by using frequency error signal obtained by Pound-Drever-Hall technique. With present system, the linewidth of a 35mW visible LD has been reduced to less than 40kHz. Using this frequency stabilized LD as a master light source, heterodyne optical phase-locking has also been carried out with Littorow configuration extended-cavity slave LD in order to evaluate applicability of our system to the OPLL. The achieved minimum square root of the Allan variance of the beat frequency fluctuation was 3.8×10^-13 at integration time of 10 sec. Throughout this phase-locking experiment, we could confirm that our master system maintained good time base stability, not showing any system instabilities such as mode hopping or disturbances.

In the study on the limit of resolution for holographic lens, an abnormality is discovered. Fourier transfer is used to analyze the limit of resolution for holographic lenses. The resolution does not follow the rule of inverse ratio with the radius of aperture. When the radius of aperture is relatively large, the resolution fits well with conventional refractive lens. However, when the radius of aperture is relatively small, with the increase of radius, the diffraction spot size increases significantly, and then rapidly decreases to normal level relative to conventional lens after reaching a maximum value.

In this paper, we show a kind of wavelength selective elements for optical communications using linearly chirped moire fiber gratings. According to the coupled-mode theory, the spectral characteristics of linearly chirped moire fiber gratings are studied. By choosing the grating length, the induced refractive index change, and the linear chirp coefficient, various optical transmission filters based on linearly chirped moire fiber gratings can be achieved. These filters are very useful for add/drop operations in wavelength-division-multiplexed (WDM) systems. A novel scheme of optical add-drop multiplexer (OADM) configuration based on linearly chirped moire fiber grating filter is proposed for flexible multiple wavelengths add-drop in WDM systems.

The effective refractive index of a guided wave depends on its polarization due to the anisotropic phase shift during the total internal reflection. Thus the grating-coupling angle is in general different for TM and TE polarized light. The compensation of this anisotropy is a difficult task. Some optical materials may present a significant birefringence when exposed to a polarized light. We would like to compensate the optical anisotropy using this photo-induced birefringence phenomenon, which would allow us to bring back the TM grating-coupling angle to the TE one. During these studies, we have developed an optical material, which allows us the formation of a relief grating via traditional light exposure techniques. At the same time, this material exhibits a significant photo-induced birefringence. This takes place thanks to the molecular reorientation phenomena after that the recording of the grating coupler is over. It is important to note that this last process does not affect significantly the grating-coupler. Furthermore we have observed that photo-induced birefringence present a strong reminiscence after the pump beam deactivation. The grating coupling experiments with and without the photo-induced phenomena were conducted.

All polarization maintaining fiber Sagnac interferometers with linearly birefringence are proposed for the construction of stable comb filters. The transfer functions of the filters can be determined if stress-induced birefringence fiber is used because its birefringence is more or less independent of wavelength. The transfer function of the simplest filter, which acts as a comb filter, with only one polarization mode-coupling point is obtained. Several filters have been realized; they exhibit channel isolation of about 22 dB and can be used as frequency selectors in multi-wavelength fiber lasers. We also discuss the potential applications of the proposed filter that include add-drop multiplexers in wavelength division multiplexing (WDM) systems, gain flattening in fiber amplifiers, and switches/modulators.

A passively quenched single photon counting avalanche diode (PQ-SPAD) is integrated in a conventional CMOS process. Co-integration of passive quenching circuit and photodiode leads to a robust pulse and a dead time as low as 32ns. The FWHM timing resolution of the PQ-SPAD is 50ps. The 30mm2 photosensitive area photodiode has a maximum photon detection probability about 20% at λ=460nm, 5% at λ=700nm and 1% at λ=900nm. The dark count rate is 300Hz at room temperature and follows a poissonian distribution. By a cooling of the detector at -20°C, a dark count rate in the 10Hz range can be obtained. The afterpulsing probability is 2.5% at room temperature with 80% of the afterpulses located in the first 100ns after the avalanche event. The PQ-SPAD is well suited for detection applications in the visible and near infrared wavelengths and where the light can be concentrated on the active area using a high magnification objective. The PQ-SPAD also offers gated operation possibility for applications where the arrival of the photons is known. Due to its outstanding characteristics obtained at very low cost, the PQ-SPAD element opens the way to integration of detector arrays.

When a photonic device is directly butt-coupled to a single mode fiber, often there is a 90% or more optical power loss, due to their highly unequal spot-sizes. Often, by using complex microlenses, the coupling efficiency has been increased, but however at the expense of a sub-micron alignment tolerance requirement, and consequently higher associated cost for a reliable operation. Recently, monolithically integrated devices, mostly using tapered structures, have been reported as useful to modify the spot-size of semiconductor photonic devices, which could assist in the rapid implementation of 'fiber-to-the-home'. In this work, spot-size converters with a tapered core, also using novel uniform directional couplers and MMI structures are discussed. A rigorous numerical approach, based on the full vectorial finite element method, is used to design various types of monolithically integrated spot-size converters for efficient coupling to an optical fiber and results of their performance reported.

We demonstrate Digital Optical Switches (DOS) on InP based on carrier-injection and on the quantum-confined Stark effect (QCSE). The active waveguide core is composed of either a double-heterostructure of InGaAsP for carrier-injection or a InGaAs-InGaAsP for reverse bias operation. O-Ion implantation was employed to isolate the branches of the DOS instead of the usual isolation by etching employed elsewhere.

Bit error rate (BER) performance comparison in a FFH-OCDMA system with incoherent and coherent optical sources is performed by using a superfluorescent fiber source as an incoherent source and a single-mode multiwavelength fiber laser as a coherent source. Experimental results show that, the power penalty associated with the beat noise is approximately 1 dB. A measurement of the beat noise RF spectrum, with a matched encoder/decoder pair, is also performed and compared to numerical calculations.

Although population dynamics play an important role on the characteristics of laser emission, the polarization properties of fiber lasers are established by the birefringence of the laser cavity. While the use of fibers with low birefringence (Low-Bi) will yield polarization features that can be easily altered by means of polarization controllers, fibers with high birefringence (Hi-Bi) yield more stable polarization features. Although in most cases stable oscillation frequencies from a fiber laser are desired, some applications require adjustments either on the spectral or the polarization characteristics of the laser output. This can be easily achieved by combining both Hi-Bi and Low-Bi fibers to form a hybrid birefringence resonator. In this paper we study the transmission characteristics for these fiber resonators using Jones matrix analysis. This yields information on relevant laser characteristics as a function of different parameters for the Low-Bi and Hi-Bi fibers (e.g., birefringence, length and orientation of the birefringent axes). In particular, we focus on the theoretical predictions on tunability of polarization mode beating frequencies (PMB) as a function of wavelength and effective birefringence of the laser cavity. The results are compared with experiments involving fiber polarimetric sensors, tunable optical generators of microwaves and wavelength measurement of fiber lasers through PMB frequencies.

Theoretical analysis has shown that a switched optical bridge (Sw-OB), in which a single beam is alternated between the reference and measurement optical paths, has the potential of rendering sensitive measurements of transmittance variations in optical devices. For a laser source with adequate switching characteristics, measurements limited by the shot-noise of the photodetectors are predicted. This paper demonstrates the feasibility of realizing a polarization switched fiber laser that could find direct application for Sw-OBs. Full switching between two orthogonal polarization states is achieved by adjusting the coupling between the polarization modes and by varying the losses for each mode independently. Although some bulk optical elements are used for this demonstration, an all-fiber version of the proposed laser configuration could be realized by using polarization sensitive fiber devices.

We consider the formation and stability characteristics of bound states in the complex Ginzburg-Landau equation. Using the perturbation theory, we derive a dynamical system describing the interaction between two weakly overlapping pulses. Two types of bound states were found, which correposnd to fixed points of this system. One of them is unstable, while the other corresponds to practically stable stationary points of the dynamical system governing the interaction. Our numerical results indeed confirm the existence of stable bound sttes of two solitons when thephase difference between them is plus or minus π/2. This happens when we consider the interaction of both two standard plain pulses and of two composite pulses. We find that two-composite pulses bound states have zero velocity, which is contrast with the behavior of the bound states formed by plain pulses. The existence of stable bound states with zero velocity formed by multiple composite pulses is also demonstrated.

Fiber optic temperature sensors based on fluorescence decay and using a monolithic crystalline construction are described. Results obtained with YAG probes terminating in Er:YAG and Yb:YAG tips are reported. To date temperature as high as 1,900 K has been reached with the Yb:YAG sensor. Issues to be addressed in the future development of this type of temperature sensor are discussed.

This paper describes implemented methods for characterizing a 5-bit programmable dispersion matrix (PDM) that is built to control a two-channel Receive beamformer in the 1550 nm region. The architecture of the PDM, is based on an array of 5 delay lines each having two spliced fiber Bragg gratings. Phase measurements for 32 possible delay configurations of the PMD are presented. Beam-patterns of this Receive beamformer at RF frequencies of 0.2, 0.5 and 1 GHz agrees well with the theoretical calculations. The main lobe of the beam pattern is shown to be independent of frequency for several target positions thus demonstrating a 'squint-free' characteristic of this optical processor.

A single sideband suppressed-carrier (SSB-SC) optical modulator is demonstrated. The sideband is suppressed by means of a fiber Mach-Zehnder interferometer with amplitude electro-optical modulators in each branch. The attenuation of the carrier is achieved by proper biasing of the integrated modulators. The proposal was demonstrated by modulating at 285 MHz. Suppression of 30.8 dB in the carrier and 26.3 dB in the sideband were obtained.

The design of a grating assisted directional coupler filter is outlined for a chalcogenide glass based device. The refractive index dispersion for As₂Se₃ is given and design equations are heuristically developed. Sensitivity analysis of these equations suggests a quick, inexpensive, and effective means to correct for the exponential sensitivity on waveguide separation in directional coupler based designs. Filter characteristics are found with the transfer matrix method and a simple tapering methodology is introduced to allow for realizable devices.

In silica glass frozen-in temperature of glass structure, so-called the fictive temperature, is strongly related to optical properties such as the Rayleigh scattering intensity and location of ultraviolet absorption edge. We investigated these optical properties with respect to the fictive temperature of samples with various fluorine concentrations. Furthermore, the structural relaxation during glass forming process was systematically examined. We have found that doping of fluorine strongly encourages the structural relaxation and lowers the fictive temperature. We have also found that relations between the fictive temperature and the optical properties vary sensitively to fluorine concentration.

Many papers were recently dedicated to the lab-on-a-chip applications, where all the basic elements should be integrated directly onto the microchip. The fluorescence spectroscopy is mostly used as a detection method due to its high reliability and sensitivity, but requires light source and photo-detector. For the first time, we then propose to use Organic material Light Emitting Diode (OLED) to supply a light source for the optical detection based on fluorescence spectroscopy. By combining this OLED with micro-fluidic channels patterned in PDMS layer, the integration of light source on the chip is then achieved. First, the ability of Organic Material to excite fluorescent response from dye is demonstrated. Then, some configurations are described in order to decrease the major drawbacks that have to be solved before applying such kind of devices.

Using a rigorous full vectorial beam propagation model, based on the versatile finite element scheme, a novel design of polarization converters based on single or multiple curved waveguide sections is presented. The performance of the polarization rotator is evaluated and optimized in terms of the polarization conversion ratio, the device length and the scattering losses. Also, a study of the sensitivity of the device performance, with respect to different fabrication parameters has also been performed.

Spectroscopic optical coherence tomography (OCT) is accomplished by analyzing fringe-resolved coherent functions that are obtained by Fourier transform of spectral interferogram. By use of this analysis, spectral absorption and dispersion properties are obtainable. We also constructed a simple model and discussed the accuracy of this technique.

This paper proposes a neural network-based technique for improving the quality of the image fusion as required for the remote sensing (RS) imagery. This proposes to exploit information about the point spread fucntions of the corresonding RS imaging systems combining it with prior realistic knowledge about the properites of teh scene contained in the maximum entropy (ME) a priori image model. Applying the aggregate regularization method to solve the fusion tasks aimed to achieve the best resolution and noise suppression performances of the overall resulting image solves the problem. The proposed fusion method assuems the availability to control the design parameters, which influence the overall restoration performances. Computationally, the fusion method is implemented using the maximum entropy Hopfield-type neural network with adjustable parameters. Simulations illustrate the improved performances of the developed MENN-based fusion method.

The system outage probabilities (probabilities that BER>10-12) due to polarization mode dispersion (PMD), polarization dependent loss (PDL) and their combination are calculated for 10 and 40 Gb/s systems. It is found that the combination of PMD and PDL has a stronger impact on 40 Gb/s system than on 10 Gb/s system.

A new waveplate model of polarization mode dispersion (PMD) is proposed. Using finite number of polarization maintaining fiber (PMF) sections in the new model, it can generates any differential group delay (DGD) values, while the conventional model produces zero possibility beyond certain DGD range. Importance-sampling technique is used to simulate the DGD probability density at large DGD range. Simulation results show that the DGD probability density function generated by the new model is Maxwellian even when the probability density is as low as 10^-35.

When irradiating particular biological media in general there will be a range of optical properties to deal with, with respect to the irradiating wavelength, and the respective tissues that make up the organ under treatment or being imaged. In addition to this we saw changing optical properties under influence of denaturization, dehydration and carbonization. We also observed optical nonlinearities that are irradiance dependent, in addition to the birefringence which affects the light distribution throughout the tissue differently than the polarization birefringence used in optical polarization microscopy. In the treatment of ventricular tachycardia with laser photocoagulation the success of the procedure depends on whether sufficient energy has been directed to the relevant region of the myocardium to ablate the entire arrhythmogenic focus. A new high power diode laser operating in the near infrared was used in an animal infarct model and in human arrhythmia ablation. The light distribution measured for Chagasic heart tissues at the diode laser wavelength demonstrated the key potential to create controlled deep photocoagulation lesions. From our observations we may conclude that the diode laser - catheter combination offers significant potential for the elimination of arrhythmia's resulting from Chagas disease.

Periodontal disease is a term used to describe an inflammatory disease affecting the tissues surrounding and supporting the teeth. Periodontal diseases are some of the most common chronic disorders, which affect humans in all parts of the world. Treatment usually involves the removal of plaque and calculus by scaling and polishing the tooth. In some cases a surgical reduction of hyperplastic tissue, may also be required. In addition, periodontitis is a risk factor for systemic disorders such as cardiovascular disease and diabetes. Current detection methods are qualitative, inaccurate, and often do not detect the periodontal disease in its early, reversible stages. Therefore, an early detection method should be implemented identifying the relationship of periodontal disease with erythema. In order to achieve this purpose we are developing an optical erythema meter to diagnose the periodontal disease in its reversible, gingival stage. The discrimination between healthy and diseased gum tissue was made by using the reflection of two illuminating wavelengths provided by light emitting diodes operating at wavelengths that target the absorption and reflection spectra of the highlights of each particular tissue type (healthy or diseased, and what kind of disease). Three different color gels could successfully be distinguished with a statistical significance of P < 0.05.

A novel fiber design has been proposed for a (+D) Non Zero Dispersion Shifted Fiber (NZDSF). The obtained characteristics of this fiber (such as Petermann II-Mode Field Diameter, Group Delay, Group Velocity Dispersion, Dispersion Slope, and Effective Area) are in good agreement with the commercially available (+D) NZDSF with the trade name LEAF.

Based on the exciting results recently achieved using the finite-difference time domain (FDTD) method, an explicit two dimensional FDTD package for modeling wave propagation in certain kinds of nonlinear media such as 2nd-order nonlinearity, 3rd-order nonlinearity, Kerr effect, Raman effect is proposed. The proposed scheme adopts the polarization equation (PE) philosophy, where all nonlinear effects are expressed by nonlinear polarization terms in the time-space domain Maxwell's equation. The Lorentz dispersive effect in time domain polarization term can also be easily coupled in this scheme, which will lead to a dispersive nonlinearity simulation. Typical examples for pulsed beam self-focusing, scattering, harmonic response are presented in this paper.

The creation of microchannels in a photosensitive material, the arsenic trisulphide As₂S₃, is reported. It is shown that microchannels are created through the process of self-writing and are very sensitive to the photosensitivity of the material, the quality of the incident wavefront and the light intensity. The very large photosensitivity of As₂S₃ allows for the self-written waveguide to become much smaller than the incident beam. It can indeed be as small as 1 micron wide. We present a numerical analysis based on the nonlinear Schroedinger equation that accounts well for the diversity of the microchannels experimentally observed. It is also shown that the microchannels can actually guide light efficiently.

This paper presents a novel 2D-scanning micro-mirror used in ECOM for in vivo and in situ tissue imaging using MEMS technology. The 2D scanner accomplishes Raster Scanning with just one mirror. The size of the mirror is 1mm by 1mm and is rotated about two axes giving it two degree of freedom. The scanning mirror is actuated electrostatically. The inherent disadvantages of electrostatic actuation such as high crosstalk between electrodes, and large nonlinearity in voltage to angle relationship are systematically addressed. In the context of biomedical applications, it is desirable to minimize the driving voltage requirements of the electrostatic actuators while maintaining the same scan angle. The optical scanner described in this paper is capable of generating large scan angles with low driving voltages, thus making it highly suitable for biomedical imaging.

Spectral interference caused by structured thin-film components has been used for shaping and characterization of few-cycle femtosecond laser beams. Array structures enable spatially resolved measurements of coherence and wavefront. The generation of spatially and temporally localized optical wavepackets with reflective and refractive axicons was demonstrated in theory and experiment.

Since the late 1990s, steady advances in wavelength division multiplexing (WDM) technology have provided better ways to increase the capacity of optical networks. Three significant trends become evident in long-haul transmission system, namely the continual increase in the number of dense WDM channels, the increase in data rates from 2.5 Gb/s to today's 10 Gb/s, to tomorrow's 40 Gb/s, and finally longer distances between electrical regeneration sites. These trends towards an increased optical network capacity are now clashing with chromatic dispersion. This paper will discuss the application of high-end FBGs to telecommunication systems, focusing on their performances with respect to chromatic dispersion. Two types of components will be discussed: low-dispersion FBG WDM filters and FBG dispersion compensators. High-quality ultra-low dispersion FBGs have been fabricated successfully and their key attributes will be discussed. Advanced applications of FBGs for chromatic dispersion compensation, such as broadband multi-channel dispersion and slope compensation, will be covered. In particular, FBG dispersion slope compensators can be used in conjunction with Dispersion Compensating Fiber (DCF) to fully manage the dispersion over a large number of WDM channels. The need for tunable dispersion compensation at 40 Gb/s transmission rates will be discussed. Experimental results will also be presented.

Multi-wavelength sources are very attractive for optical telecommunication applications. Recently, several proposals have been made to use a frequency-shifting element inside a fiber laser ring cavity to realize a continuous wave (CW) multi-wavelength source operating at room temperature. In this type of laser, the frequency shift, introduced by an acousto-optic device, prevents the single frequency emission expected from the usual homogenous gain broadening behaviour of erbium-doped fiber. However, it has been previously observed that these sources can emit pulsed or CW radiation. In this paper, we describe the different emission regimes and we experimentally examine the impact of several key parameters on the optimization of the CW emission. To this end, a temporal characterization of the laser output was performed as a function of the cavity length, the number of simultaneously lasing wavelengths, the cavity loss, the erbium doped fiber length and the pump power. We found that an important parameter was the optical intensity circulating in the cavity. Indeed, the accumulated nonlinear phase shift and the amplifier saturation level are directly related to the intra-cavity laser field. By increasing the cavity loss or the number of wavelengths, the CW emission can be favoured over the mode-locked emission regime.

A novel method of measuring the polarization dependent loss (PDL) and the polarization mode dispersion (PMD) of fiber Bragg gratings (FBGs) is proposed and demonstrated experimentally. This method eliminates the influence of components (e.g. circulator) on the PDL and PMD characterization of FBGs. The experimental results are compared with those measured using other methods.

Laser micromachining may be used for a variety of applications including drilling holes or creating trenches in dielectric materials. Cracking around the ablated features can be a significant problem for many applications, particularly when micromachining glass. One possible method for crack reduction, investigated here, involves heating of the substrate during ablation. This leads to a more ductile material that is more able to withstand the thermal shock of the ablation process. In order to increase the ductility, the glass targets are heated by physical contact with an electric heating element. The results of micromachining are analyzed using an optical microscope. The amount of cracking is quantified in terms of the number of visible radial cracks. For nanosecond micromachining, a reduction in the number of cracks and an improvement in the quality of the holes are observed as the glass is heated. The relative improvement using heated substrates and nanosecond pulses is also compared to femtosecond ablation of room temperature substrates.

Optical code-division multiple-access (OCDMA) is a technique well-suited for providing the required photonic connectivity in local access networks. Although the principles of OCDMA have been known for many years, it has never delivered on its potential. In this paper, we will describe the key challenges and impediments that have prevented OCDMA from delivering on its potential, as well as discuss possible solutions. We focus on the limitations of one-dimensional codes and the benefit of exploiting the additional degrees of freedom in using multiple dimensions for defining the codes. We discuss the advantages of using differential detection in order to implement bipolar communications. We then show how two-dimensional wavelength-time codes can be appropriately combined with differential detection in order to achieve high performance OCDMA systems with a large number of users operating with good BER performance for a large aggregate capacity. We also discuss the impact of channel coding techniques, for example forward error correction or turbo coding, on BER performance.

In this paper, we propose a new wavelength-reservation-based dynamic routing and wavelength assignment algorithm (RWA) to improve the fairness of previous RWA algorithms in wavelength-routed WDM networks. In the algorithm, RWA solutions available from static optimal virtual topology design are used to determine a set of wavelengths to be reserved on corresponding routes for each node pair. Based on the wavelength reservation, a set of dynamic wavelength allocation policies is proposed to use the reserved wavelengths efficiently by allowing the reserved wavelengths to be used by others. Simulation results based on NSFNET topology show that a modified RWA algorithm based on wavelength reservation can improve the fairness of the original RWA algorithm and can reduce the overall blocking probability when traffic load is low.

In this paper, we report experimental results on a CW fiber Raman laser oscillating at 1.125μm. A CW Nd:YAG laser at 1.064μm injected in a 100m long silica fiber produces Stokes waves oscillating in a cavity formed by two fiber Bragg gratings (FBGs) written at both ends of the fiber. The fiber length and the output coupling were chosen after a numerical analysis for an optimization of the output power. An output power of 1.5W at 1.125μm has been experimentally obtained.

We describe an interferometric method for phase difference amplification in near real-time using an optically addressed liquid crystal spatial light modulator (LCSLM). The LCSLM has a rise time of 30ms and a decay time of 40ms, a resolution of 50 lp/mm, and a diffraction efficiency of 30%. The interference fringes obtained by a Michelson interferometer serve as input into the write side of the LCSLM and two beams are used to illuminate the read side. The nonlinearity of the LCSLM recording material produces the high-order diffracted beams. The nth and -nth order diffracted beams interfere with each other and the phase difference amplification is carried out in near real-time. We have demonstrated that it is possble to achieve phase difference amplification by a factor of 6 using phase stepping methods.

We investigate the use of differential detection in two-dimensional (2D) wavelength-time Optical Code-Division Multiple Access (OCDMA). We develop and analyze the bit-error-rate (BER) performance for a new family of high-weight 2D codes with relaxed auto- and cross-correlation, which we call balanced codes for differential detection (BCDD), that take advantage of the antipodal signaling strategy enabled by differential detection. We find that BCDD's can effectively be used to implement high-performance 2D wavelength time OCDMA networks. Using an OC-3 transmission rate of 155Mbps, a BCDD system with 32 wavelengths, 41 time-chips and suitable error-control coding can support up to 320 users with bit error rate of 10-9, giving rise to an aggregate capacity of 41Gbps.

The thulium-doped ZBLAN fiber laser converts infrared radiation in the range 1100-1160 nm to visible radiation around 480 nm through an upconversion pumping process. A brief description of the laser through a rate equation analysis modeling is presented. A compact experimental setup using a diode-pumped Yb³⁺ fiber laser at 1108 nm is presented. Single transverse mode blue emission at 482 nm with a maximal output power of 96 mW was obtained. A slight increase of the laser threshold due to photoinduced losses from 103 mW to 240 mW was observed, which is significantly less than previously reported values. Further optimization of the laser efficiency is proposed using Raman fiber laser pumping at 1125 and 1160 nm. Numerical simulations are used to calculate the expected increase in blue output power.

In this work we present the development of an optical probe which can be used to measure the absolute value of the real and imaginary parts of the refractive index of transparent, opaque or turbid liquids indistinctly. The device can work as a portable, immersion-type, critical-angle refractometer or as a high resolution optical sensor to monitor physical or chemical processes in liquids. The instrument is based on scanning laser reflectometry and measures the reflectance angular-profile around the critical angle. It also measures directly the angle-differential profile of the reflectivity by dynamic reflectometry. For sensing variations of the RI, one can monitor in time either the reflectance or its angular derivative in the vicinity of the critical angle. The uncertainty of the instrument in measuring the real part of the RI can be 10^-6. The sensing resolution can be 10^-7 when monitoring the differential reflectivity. When the RI is harmonically modulated in time (of RI), it is possible to achieve a resolution as high as 10^-10. The applicability of the technique to turbid media consisting in suspension of particles is briefly discussed. We also show that the RI of liquid sample can be monitored through a physical or chemical process if the liquid is vigorously stirred. Regarding the instrument design, we use a novel mechanism to control the angle of incidence which allows to keep all components fixed (laser, detector, semi-cylindrical lens, angle modulator, and cables), except for a mirror and a collimating lens. It only requires linear displacements, for which a conventional micrometer is enough. This design is a considerable improvement over the typical laboratory arrangement used by several authors, and permits to have a portable, compact instrument with all the capabilities of the laboratory technique. The design offers a wide measurement range as to cover most water solutions. We believe the device offers an acceptable balance between size and stability. We give results obtained with an experimental prototype of the device. The aim of this work is a general overview of the foundations of the technique, the development of the sensor and some applications.

We are studying the loss and the dispersion compensation properties of tapered silica capillary for applications in multiwavelength optical communications. The 40-micron Xenon core (1.000702 refractive index) is confined by a 22-mm wall thickness silica capillary. The wall presents Fabry-Perot resonances at 55-nm intervals in the 1500-nm band. With resonances as sharp as 1.5 nm such capillaries could serve as stable inexpensive fibered Fabry-Perot reference filters and also serve as chromatic dispersion compensators. Helium gas (1.000035 refractive index) surrounds the capillary. Extensive numerical simulations and experimental results show that including gases in the core and the external medium allows low-loss propagation of the power and support monomode guidance. This new structure will provide strong dispersion compensation for this device.

The interest in propagation invariant optical fields (PIOF's) is due to the fact that, under optimal conditions, they propagate long distances without significant change of their transverse intensity distribution. These kind of wavefields were first identified and described in terms of Bessel function. Based on the separability of the Helmholtz equation in elliptic cylindrical coordinates we have demonstrated that there exist another class of PIOF's. The lowest order mode may have a highly localised distribution along one of the transverse directions and a sharply peaked quasi-periodic structure along the other. Higher order modes are composed of elliptical vortices and the corresponding intensity profiles are formed by propagation-invariant confocal elliptical rings. These fields are described by the Mathieu-Hankel functions which are exact solutions of Helmholtz equation and for this reason we have called them Mathieu beams. We demonstrate that Bessel beams are a particular case of Mathieu beams, which have a broader fan of interesting features. Since the Mathieu functions form a whole set of exact travelling wave solutions of the Helmholtz wave equation they can be used to describe a class of PIOF's. The McCutchen theorem provides the relation between the general class of PIOF's and these new beams.

A simplified white-light interferometric strain sensor based on HB fibers with automatic temperature compensation is presented. A variety of experiments conducted within this study confirm an adequate temperature compensation could be achieved. Several different sensor structures were investigated during these experiments. One of the most important results shows that the interference contrast could significantly influence the measurement accuracy achievable by the system. Consequently, a 1% or even better absolute accuracy for short sensing fibers is possible if the contrast is enhanced to 0.5. A quasi-distributed cascade containing several discrete sensors with 0.5 contrast is also suggested.

In this paper, we analyzed the system power penalty induced by the coherent crosstalk components as the dominant crosstalk channel in WDM-OXC, and present a simple expression, which can be readily calculated by popular software. We also present an expression of the power penalty when both incoherent and coherent crosstalks are presented. The simulation results show that by introducing a bit pattern mismatch method in a WDM-OXC, the extra penalty caused by the coherent crosstalk can be distinctively suppressed.

We show numerically and experimentally that ring dark spatial solitons can be generated using a phase disk mask or an opaque ring. In the first case one ring is produced and in the second a pair. Rings generated by phase disk are very stable when they are perturbed with one-dimensional dark solitons. The stability of rings generated by opaque rings depends on the size of the perturbation and symmetry of the initial condition. The propagation and stability of these solitons is analyzed numerically and experimentally.

We describe all-optical transistor action in photonic band gap materials doped with active atoms. In the presence of a photonic band gap (PBG) material, a coherent laser beam with the frequency slightly detuned from the resonant atomic transition frequency can drive a collection of two-level atoms to an almost totally inverted state, a phenomenon strictly forbidden in ordinary vacuum. By changing the laser field intensity in the neighborhood of a threshold value, it is possible to drive the atomic system through a transition from states in which the atoms populate preferentially the ground level to almost totally inverted states. In this process, the atomic system switches from a passive medium (highly absorptive) to a active medium (highly amplifying). The switching action in a PBG material is not associated with operating near a narrow cavity resonance with conventional trade-off between switching time and switching threshold intensity. Rather it is associated with an abrupt discontinuity in the engineered broad band electromagnetic density of states of the PBG material. We demonstrate all-optical transistor action in PBG materials by analyzing the absorption spectrum of a second probe laser beam and we show that the probe beam experience a substantial differential gain by slight intensity modulations in the control laser field.

The dynamical behavior of the polarization mode dispersion (PMD) in aerial field fibers is reported. A theoretical model is proposed to simulate the corresponding PMD dynamics of an aerial fiber. A PMD emulator based on the theoretical model is constructed and it is found that the emulator can closely mimic the PMD dynamics.

Synthetic aperture is a way to overcome the spatial resolution limitation given by limited physical of an observation instrument. Active synthetic aperture techniques at optical wavelengths are presented. We show that 2D arrays of detectors overcome the co-phasing problem of the sub-pupils provided there is an overlap between each acquisition. This technique was applied to short range imaging at 633nm in laboratory environment, yielding to diffraction limited pupils 16 times larger than the original pupil without external measurement of the pupil phase history.

Bacteriorhodopsin (BR), a photoreceptor protein possesses a photochemical cycle of several distinct intermediates; all of them are photoactive. The BR molecules both in the initial form of the photocycle, BR570 (absorption maximum around 570 nm) and longest-lived (in films) intermediate M412 (absorption maximum at 412 nm) possess anisotropic absorption. Under the action of linearly polarized light, the reversible anisotropic photoselection of BR molecules takes place. So far only the method of photoinduced anisotropy based on anisotropic properties of BR570 was applied to realtime optical processing. In the present work, the potentialities for the use of photoinduced anisotropy in the BR-films based on both BR570 and M412 for the spatial light modulation are demonstrated. The overall blocking of highintensity features from an image is shown. Mixed B-M-type anisotropy in the chemically modified BR films, as applied to the edge enhancement, can provide a contrast ratio as high as 250:1. Low saturation intensity of the BR-films allows for the blocking of any intensity feature from an image that is carried out by choosing an appropriate intensity level of a controlling He-Ne laser beam without analyzer rotation. The photoanisotropic incoherent-to-coherent optical conversion with concurrent spatial-intensity modulation is also performed on the BR-films.

The electromagnetic interface states formed in a heterostructure composed of two semi-infinite Kronig-Penny photonic crystals have been studied. Modified transfer matrices have been used for study of Kronig-Penny photonic crystals (heterostructures with conducting interfaces) to show strong similarity between solid-state physics and electromagnetics. Our calculations are limited to TE polarization.

In this article, polynomial expansion approach for extraction of guided and leaky modes in layered waveguides in which loss and gain can be present simultaneously is proposed. To verify the method, results of analysis of a typical test case have been compared to the other references, proving a good agreement. Polynomial expansion is a nonharmonic expansion and does not involve harmonic functions or intrinsic modes of homogenous layers. This approach has the benefit of leading to algebraic dispersion equations rather than transcendental dispersion equation; therefore, it will be easier to solve compared with other methods such as argument principle method (APM), reflection pole method (RPM) or wavevector density method (WDM), which are solving the transcendental equation via integral methods. Besides, algebraic dispersion equation will be obtained without any numerical stability problem, while ordinary transcendental dispersion equation, which is usually derived by transfer matrix method, is difficult to obtain due to stability problem in multiplying transfer matrices.

We compare the laser performance of a-axis and c-axis grown Nd:YVO₄ crystals produced by the Czochralski method, and quantify the internal losses in the crystals. Crystal sets of 0.7%, and 0.27% Nd³⁺ dopant concentration were measured in a laser cavity pumped by an 808 nm diode laser. For both sets, the a-axis grown crystals showed higher peak power outputs, higher slope efficiencies, and lower losses.

Cobalt-doped high attenuation fibers were tested in terms of temperature, humidity, and optical power. The maximum attenuation variation recorded was less than 3% for temperatures between -40 to + 65°C under uncontrolled humidity. When the humidity was controlled, the maximum attenuation variation was less than 3% under the worst case: +85°C and 85% R.H. Optical power test were carried out at 1W and 1550 nm over 12 minutes without any recorded damage to the fibers.

Autofluorescence is widely investigated as a sensitive method in early diagnosis of diseased tissue, but most measurements of tissue autofluorescence were performed with only a single excitation wavelength. This work is aim to optimize the excitation wavelength or emission wavelength bands for fluorescence spectroscopy for better clinical diagnostic accuracy. The autofluorescence spectra of colorectal tissue were studied over a wide excitation range (350-600 nm). The excitation 350 nm and 470 nm were identified as effective excitation wavelength for inducing tissue autofluorescence. The ratio of emission peak intensity at 470 nm versus 610 nm excited by 350 nm and the ratio of emission peak intensity at 510 nm versus 610 nm excited by 470 nm were found as good indications to distinguish normal and diseased tissue. The observed peaks of the fluorescence spectra were also compared with some well known tissue fluorophores.

A thin film deposition technique has been used to fabricate conical mirrors (also called reflective axicons). The quality of the conical mirrors so produced is investigated experimentally by mechanical and optical techniques. Quasi-Bessel beams produced by illuminating these axicons with a He-Ne laser show very good agreement with diffraction theory. We also consider the generation of femtosecond (10-25 fs) optical X-waves.

We have measured the evolution of the root-mean-square (rms) duration of femtosecond pulses propagating in a dispersive medium (fused silica). Measured rms durations were compared to a theoretical propagation law based on a Pulse Quality Factor. Excellent agreement is found between theory and experiment when rms durations are evaluated with the help of the concept of fractional power.

We demonstrate a monolithic bulk shear-wave acousto-optic tunable filter which combines a piezoelectric transducer array and the acoustic interaction medium in a single lithium niobate wafer piece. By applying an rf-E_y-field, a chirped acoustic grating, formed by domain-inversion, excites an X-propagating longitudinal wave which is converted at a mechanically free boundary into a Y-propagating X-polarized slow-shear wave which itself couples collinearly propagating e- and o-polarized optical waves. A relative (absolute) conversion efficiency of 80%/W was measured at 980 nm. Regarding the filter properties the obtained FWHM in the frequency domain reflects the use of the overall length of the device as the acousto-optic interaction medium, whereas the sidelobe suppression is with approximately -3dB higher than the theoretical value of approximately -9 dB. Possible causes of such behavior are discussed and an improved design is suggested.

It has been observed that the optical noise of a Ti:sapphire laser is related to the optical noise of the laser used for its optical pumping. Argon ion lasers are largely used as optical pump for solid-state lasers, such as Ti:sapphire lasers. The intensity noise of Argon laser is transferred to the beam (or pulses) emitted by the pumped laser. In this paper, we report on the optical noise reduction of a Ti:sapphire laser, operated in continuous-wave (cw) and mode-locked regimes. This effect is achieved through the optical noise reduction of the pump laser by coupling it to a passive external cavity ended by a dielectric mirror. In the mode-locked regime, the noise reduction of the low-frequency noise components, as averaged over the interval from 100 kHz to 800 kHz, is larger than 20 dB and the maximum noise reduction is larger than 34 dB. We have also compared the noise level of the Ti:sapphire laser to the noise measured when it is pumped by a solid-state laser (diode-pumped, intracavity frequency-doubled, Nd:Vanadate laser).

Alignment stability, maintaining a minimum loss state in optical power during product fabrication, is one factor in evaluating processes and equipment for assembly and testing of fiber-optic/optical components. Cost reduction through yield improvement will require some level of alignment automation. To illustrate the changes in optical power over time and dimensional change, a 6-axis commercially available alignment robot has been characterized by aligning a single mode fiber to a single mode fiber and to a planar lightguide circuit. Optical and mechanical performance (resolution, repeatability, and stability) is presented and correlated. External factors affecting the automation system's optical performance are discussed.

Barium titanate sol was prepared using barium 2-ethyl-hexanoate and titanium isopropoxide. The sol was then spin coated on Si (100) and MgO (100) substrates and annealed at different temperatures to give polycrystalline, transparent, and crack free films. The surface morphology and structural properties of the film were studied using X-ray diffraction (XRD), Rutherford Backscattering Spectroscopy (RBS) and, Scanning Electron Microscopy (SEM).

Gelatin (G) can be described as a peptidic chain with different pendent groups among which, hydroxy groups-OH, carboxylic groups-COOH and amino groups -NH₂. Works performed on polyacrylic acid (PAA), a poymeric chain with only pendent-COOH group and on polyvinyl alcohol (PVA) with only -OH group revelaed the strong influence of the nature of the chemical structure on the photochemical behavior of dichromated photopolymers, DCG, DCPAA and DCPVA. Actually, the stability and the state of complexation of the different chromium species was completely opposite in the two matrices: the stabilization of chromium (V) resulting from the photochemical charge transfer in DCPVA, by complexation with PVA is in contrast to what was observed in DCPAA where chromium (V) was highly instable. Regarding chromium (III), the final reduction chromium species, it is complexed in PAA and not in PVA. The primary proces is identical in DCG and in DCPVA, so PVA appears as a good model of the first step of gelatin behavior. But the material obtained after irradiation and treatment of DCG only contains chromium strongly complexed by gelatin. The experiments performed on films of DC with only a few percents of PAA gave evidence for the strong influence of the presence of the carboxylic groups on the photochemical behavior: the rate of the formation and the stability of chromium species, mainly chromium (V), involved in the process. Chromium (V) appears to play a key role in the photosensitive properties of dichromated materials. The diffraction efficiencies of holograms recorded in DCPAA or DCPVA resemble the profiles of chromium (V) evolution.

Dispersion-managed soliton transmission control using either synchronous amplitude modulators or narrow-band filters is examined. Exact analytical solutions are derived for the variance of the timing jitter in both cases. We show that a complete suppresion of the timing jitter is in general possible by a conventient choice of the strength and the relative position of the modulator or of the guiding filter in the dispersion map. The asymptotic behavior of the timing jitter shows a linear dependence with distance in both cases, which is in contrast wiht the cubic dependence in the uncontrolled case.

The transmission spectra of nuclear pore membranes filled with nematic liquid crystal have been measured depending upon the transversally applied voltage. It has been shown that spectral and electro-optical characteristics of membranes with ensemble of uniformly ordered oblique pores strongly depend on the direction of polarization of incident light. The transmission spectrum of the polarized light passed through such membrane has few maxima and minima with field-varied positions on the wavelength axis. Presented results can be used to develop polarizer-free tunable color filters.

Wave-guided travelling-wave lasing (amplification of spontaneous emission in waveguide) is studied on neat films of the triphenylamine dimer 4-methyl-TPD, and of the 4-methyl-TPD phenyl substituted MEH-PPV copolymer TPD(4M)-MEH-P-PPV. Laser action is achieved by transverse pumping neat films on glass substrates with picosecond excitation pulses (wavelength 347.15 nm, duration 35 ps). Lasing occurs at 422 nm for 4-methyl-TPD and at 544 nm for TPD(4M)-MEH-P-PPV. The optical constants (absorption spectra and refractive index spectra), the absorption cross-section spectra, fluorescence quantum distributions, fluorescence quantum yields, and fluorescence lifetimes of the samples are determined for photo-physical characterization. The laser performance and the photo-physical parameters of 4-methyl-TPD and TPD(4M)-MEH-P-PPV are compared with results on MEH-PPV.

Measured and simulated power penalties were compared for 10Gbit/s NRZ loop experiments for cascaded AWG filters with 50GHz and 100GHz channel spacings. The results show that spectral flatness of cascaded filters can strongly influence the performance of high-speed systems with small channel spacing.

Pseudo near-field intensity distributions of 1-cm diode-laser bars in slow-axis plane were recorded without parasitic feedback by automated scanning with a slanted highly-reflecting thin metal wire. Irregularities in field patterns are correlated with local curvature and twisting of facets. Information on mode guiding within the semiconductor laser can be derived.

We present the design, development and characterization of volume holographic wavelength filters recorded in MEMPLEX - a new photoreactive polymer that has widespread applications in holographic technology. These holographic filters are characterized by their narrow wavelength and angular dephasing. MEMPLEX photopolymer exhibits complete lack of shrinkage during recording and post-processing, is completely self-supporting and can be fabricated to a size required by the application, has excellent optical quality, is resistant to most chemicals and has long shelf-life, it is therefore ideally suited for optical filter technology. We have recorded and characterized numerous holographic reflection volume gratings in 2 mm thick samples in order to examine the effect of writing geometry on wavelength and angle selectivity. The presented results show that efficient reflection gratings with more than 75% diffraction efficiency and linewidths of less than 0.2 nm can be recorded. Efficient wavelength filters can be used in many applications including telecom MUX/DMUX, LIDAR, spectroscopy, etc

We present a novel measurement setup that can measure the optical spectral loss (OSL) from the phase shift induced in the transmission mode and the chromatic dispersion in the reflection mode simultaneously for the chirped fiber Bragg grating. A comparison has been made between the OSL of the new method and the typical-OSL.

A new principle of lidar-radar is theoretically and experimentally investigated. The proposed architecture is based on the use of a RF modulation of the emitted light beam and direct detection of the backscattered intensity. The use of a radar processing chain allows to obtain range and Doppler measurements with the advantages of lidar spatial resolution. The maximum range of this device is calculated, taking different possible improvements into account. In particular, it is shown that the use of a pulsed two-frequency laser and a spatially multimode optical pre-amplification of the backscattered light leads to calculated ranges larger than 20 km, including the possibility for both range and Doppler measurements. The building blocks of this lidar-radar are tested experimentally : the radar processing of an RF modulated backscattered cw laser beam is demonstrated at 532 nm, illustrating the Doppler and identification capabilities of the system. Besides, signal-to-noise ratio improvement by optical pre-amplification and filtering of the ASE noise is demonstrated at 1.55 μm. Finally, a two-frequency passively Q-switched Nd:YAG laser is developed. This laser then permits to obtain two-frequency pulses with tunable pulse duration and beat frequency.

Dynamic holographic recording was performed on two fulgides (A540 and A670)/Doped films. Maximum diffraction efficiency of 7% and 6% has been achieved on A540 and A670 doped PEPC/PS films. The effects of the matrix, writing intensity and film thickness on diffraction efficiency were studied. Holographic fatigue resistance in polymer matrix and epoxy resin has been investigated. It was found that holographic fatigue of fulgide doped in epoxy resin is closed to zero at least after 40 Write-Read-Erase cycles (WRE).

We investigate the recording dynamics of Omnidex photopolymer film from DuPont. We use a reviewed version of the diffusion model proposed by Zhao and Mouroulis in order to describe the recording response, that combine photopolymerization and free monomer diffusion process. Experiments are presented that lead to the determination of material kinetic parameter. These values are introduced in a numerical model to provide quantitative simulation of gratings formation under various holographic exposures. We extend its application to the investigation of film shrinkage influence on refractive index distribution and spectral selectivity of reflection gratings. This study improves the understanding of recording process and consequently allows building more accurate holographic components in this material.

The formation of holographic gratings in an azo-glass is investigated for the simple case of an intensity grating in the s-polarization of the recording beams. A dual grating is formed as a function of time with a refractive index grating and a relief grating. The diffraction efficiency as a function of recording time is discussed in a model of 2 consecutive processes with a phase shift. A material transport process is involved in the formation of relief patterns. A thermal erasure process at the glass transition is compared with an optical process.

We report 3D photonic crystals of polystyrene micro-spheres and air spheres in Barium titanate Background with diameters between 220 and 1100 nm by filling the voids (between the polystyrene micro-spheres) with Barium titanate. The BaTiO₃ was synthesized from a sol gel solution. The polystyrene is then removed by calcination. The pyrolysis at 550°C enables to make the right phase of BaTiO₃. Scanning electron microscope and optical microscope confirm the quality of the samples. The structure strongly diffracts light and can be a step to photonic band gap materials.

In several recent papers, layered waveguide structures with conductive interfaces have been discussed, whose propagation properties are controlled by a transverse voltage. These structures can be used as a dynamic optical read/write memory cell, and programmable optical diffractive element. In this paper, the excitation of surface waves with the presence of interface charges is discussed. Interface charges affect the dispersion of surface waves, and therefore they can be used in various applications such as optical modulators, switches, sensors and filters. These waves can be superior to surface plasmon waves since they are not lossy. The lossless property is satisfied in limited range: millimeter waves to far infrared.

Broad area lasers (BALs) with external Fourier-optical cavities with spatial filter for transverse mode selection are investigated experimentally and numerically. Nearfield and farfield distributions are calculated and compared to experimental results. Two different BALs, one with a high (10%) and the other with a very low residual reflectivity of the output facet (facing the external resonator) are operated in external Fourier-optical 4f setups. For the BAL mentioned first, transverse mode selection is obtained at low pump currents; the emission of the fundamental or a specific higher order transverse mode can be stabilized. In the latter BAL transverse modes can be selectively excited up to pump currents more than 200% above laser threshold. Numerical calculations reveal, that if this BAL within an external 4f-cavity is pumped even higher above laser threshold, it starts to operate in a self-Q-switched mode. Pulse duration and repetition rates are in the range of 2-4ns and 100-200MHz, respectively. Also, the concept and technology for fabrication of compact, miniaturized hybrid integrated Fourier-optical external cavities based on polymer waveguide mirrors is described. Experimental results of transverse mode selection in BALs with hybrid integrated-optical cavities are presented.

A novel fiber optic sensor technique utilizing hetero-core structure is reported based on surface plasmon resonance (SPR) sensor for refractive index detection. The sensor makes it possible to interrogate between evanescent light wave of the light and outer environment by deliberate leaking of the transmitted light wave into the cladding region. Surface plasmon wave (SPW) due to evanescent wave is excited in a silver film coated on the cladding region of the sensor portion. Experiments were carried out with white light source and glycerin solutions as an analyte. Sensor response has shown sharp SPR curves and their dip shift toward the longer wavelength by increasing the concentration of the sample solution. It has been demonstrated that the hetero-core structured fiber optic sensor could be worked as a spectral, and an amplitude SPR sensor.

In this work we have shown that Stimulated Raman Scattering can be effectively controlled by a fiber bending losses resulting in spectral dependence of the fiber attenuation.

The Atmospheric Chemistry Experiment (ACE) is the mission selected by the Canadian Space Agency for its next science satellite, SCISAT-1. ACE consists of a suite of instruments in which the primary element is an infrared Fourier Transform Spectrometer (FTS) coupled with an auxiliary 2-channel visible (525 nm) and near infrared imager (1020 nm). A secondary instrument, MAESTRO, provides spectrographic data from the near ultra-violet to the near infra-red, including the visible spectral range. In combination the instrument payload covers the spectral range from 0.25 to 13.3 micron. A comprehensive set of simultaneous measurements of trace gases, thin clouds, aerosols and temperature will be made by solar occultation from a satellite in low earth orbit. The ACE mission will measure and analyze the chemical and dynamical processes that control the distribution of ozone in the upper troposphere and stratosphere. A high inclination (740), low earth orbit (650 km) allows coverage of tropical, mid-latitude and polar regions. This paper will describe the metrology scheme, based on an IR laser diode, as well as algorithms that are needed to fully calibrate, along the wavenumber axis, the spectra measured by the ACE instrument.

The emerging technology of micro-optical-electro-mechanical systems (MOEMS) offer promise for automating the alignment of free-space optical systems, especially intra-computer optical interconnects. MOEMS-based microlenses and micromirrors have been fabricated for the purpose of providing initial system alignment and dynamic alignment.

The development of devices for biological and chemical analysis is a new and exciting application of micro-electro-mechanical systems (MEMS) technology. In this paper, a method for integrating multimode optical waveguides within glass biochips with fluidic microchannels is described. The waveguides buried in the glass are designed to carry probe light to the channels, capture any emission from samples therein, and deliver the emitted light it to a sensitive photodetector. The ultimate goal is a self-contained, operatorless analysis system for mass testing of biological samples. The field-assisted silver ion-exchange process for fabricating the multimode waveguides and some preliminary results on the waveguide properties are described.

We analyze linear and no linear optical properties of PMMA clusters in thin film s with Ni nanoparticles dispersed with different concentrations. Saturable absorber and negative nonlinear refraction index behavior evidences were found using z-scan technique. We also show that these properties have not dependence of the type of matrix but they have on concentration.

The Sagnac interferometer of twisted low-birefrigence fiber is analyzed numerically in the lineal region. A method for measuring the birefringence of the fiber and the angle of rotation of the axes inside the fiber loop of the interferometer is also presented.

An experimental investigation of the dynamical, time depends effects in the reflection of (2+1)D beam at the nonlinear interface between photorefractive crystal SBN61:Ce and a linear medium is performed. Our study make emphasis on determining the physical condition under which the beam reflected by the interface is still a focusing beam.

Fiber-optic Bragg grating filters are fabricated with a range of Bragg wavelength between 1296 and 1336 nm, using a single phase mask. 30 mW of continuous-wave light at 244 nm is used from a frequency-doubled argon-ion laser having an intracavity etalon. Gratings are fabricated by tilting the photosensitive fiber with respect to the phase mask up to an angle of 15 degrees. The variation of Bragg wavelength with the fiber-tilt is explained with a simple formula. High spatial coherence of 244 nm light makes it possible to displace the fiber as much as 6 mm in front of the phase mask and tilt the fiber by as much as 15 degrees. This results in nearly constant band-width and near 100 % reflectivity for all gratings throughout the 40 nm range.

We demonstrate for the first time the use of a new borate crystals: Yb:GdCOB and Yb:BOYS in femtosecond mode-locked oscillators. Pulses as short as 69 fs for the Yb:BOYS and 89 fs for the Yb:GdCOB have been obtained near 1 µm.

Interrogation techniques for fiber Bragg grating sensor arrays need particular attention in the case of structural health monitoring applications involving dynamic strain measurement. Typically the performance of the sensing system is dependent on both the sensor type and the interrogation method employed. A novel interrogation system is proposed here that consists of different interrogation units for each sensor in the array, each unit comprising of a circulator, chirped grating and a Mach-Zehnder interferometer. We present an analysis that consists of tracking the spectral changes as the light passes through various elements in the interrogation system. This is expected to help in the optimization of sensor and interrogation elements leading to improved performance of the health monitoring system.

Fiber Bragg-gratings are embedded in carbon-epoxy laminates as well as bonded on the surface of composite wound pressure vessel. Structural properties of such composites are investigated. The measurements include stress-strain relation in laminates and Poisson's ratio in several specimens with varying orientation of the optical fiber Bragg-sensor with respect to the carbon fiber in an epoxy matrix. Additionally, fiber Bragg gratings are bonded on the surface of cylinders fabricated out of carbon-epoxy composites and longitudinal and hoop strain on the surface is measured.

The noise and mode-locking phenomena of a hybrid soliton pulse source (HSPS) utilizing Gaussian apodized fiber Bragg grating is described. The HSPS is modeled by a time-domain solution of the coupled-mode equations including spontaneous emission noise. Relative intensity noise (RIN) is calculated using numerical solutions of these equations. It is found that near transform limited pulses are only generated over a limited frequency range even if system is properly mode-locked over a wide frequency range around the fundamental mode-locking frequency. If transform limited pulses are not obtained at the fundamental frequency, output pulse is not more affected from the noise at this frequency. It is also found that noise reduction is possible by using these gratings.

The contamination of fiber optics connectors has recently been recognized as an industry wide problem. The contamination has resulted in degradation of optical signal performance, which creates false fails during the manufacturing process. These contaminated fiber optics connectors require additional manufacturing operations such as inspection of incoming components, cleaning process and re-inspection. The cleanliness of test connectors is also very important to ensure good product quality. The dirty connectors in the test environment create false functional failures at the board level, resulting in unnecessary and costly rework. All precautions have to be taken to identify the critical steps in the manufacturing process that cause the contamination to the component, assembly or board levels. The potential sources of contamination and the mechanisms of the transferring contamination have been analyzed.

The problem of the linewidth degradation in systems using distributed-feedback lasers together with strained-layer multi-quantum-well semiconductor optical amplifiers (SOAs) is examined. A numerical model combining finite element calculations in the transverse x-y plane and a longitudinal model based on the Green's function method is used for that purpose. Simple expressions for the linewidth in the case of AR-coated SOA output facets are derived and simulation results are given in the case of an output facet with a non-vanishing reflectivity. It is found that optimal conditions for a narrow linewidth can be determined.

We have experimentally studied pattenr control in a unidirectional photorefractive oscillator in which a barium titanate crystal is used to provide two-wave mixing gain. The crystal is pumped with a single frequency argon laser and the cavity length is actively stabilized. The output of the photorefractive oscillator is sent to a feedback arm that consists of two mirors and two lenses. The lenses are arranged to form a 4f-system. Spatial filtering is implemented by placing a mask in the Fourier plane in the feedback arm. The relative phase difference between the feedback signal and the oscillating beam is changed with a piezoelectric translator attached to one mirror in the feedback arm. Using this contorl theme we can change the output pattern, e.g., from a Gauss-Laguerre mode to an Gauss-Hermite mode or to suppress and enhance side lobes in a pattern.

We report on the performance of a 3.2 Gb/s VCSEL driver implemented in foundry n-well 0.18μm CMOS technology. The VCSEL driver utilizes a novel push-pull circuit topology that pushes and pulls modulation current into and out of the VCSEL cavity thus producing symmetric rising and falling edges. Using a commercial VCSEL with a threshold current of 1.2 mA and a slope efficiency of 0.3 mW/mA, the circuit was operated at 1.25, 2.5 and 3.2 Gb/s and produced 2.5 mW of average optical power.

Strength and dynamic fatigue behavior of silica optical fibers has been measured in very dry atmosphere. Bare and coated fibers were compared to characterize the influence of the polymer. The stress corrosion susceptibility parameter has been evaluated. Subcritical crack growth effect was found to be different in coated and bare fibers while their strength was found to be close. The strength measurement have been done using a two-point bending set up.

We report here uncooled and thermoelectrically cooled InAs photodetectors designed for fast and sensitive detection of IR radiation. This has been achieved by the use of a complex architecture of the device that ensures reduced thermal generation of charge carriers, fast diffusion and drift transport of photogenerated carriers across the absorber region, a low series resistance, and a low capacitance. In addition, the device are monolithically immersed to GaAs hyperhemispherical microlenses that reduces capacitance by more than two orders of magnitude in comparison to non-immersed devices of the same optical area. As a result, the optimized devices are characterized by picosecond response time.

Investigation of electro-optic modulation in nonlinear materials placed within a Fabry-Perot modulator cavity is presented. Enhanced modulation at lower driving voltages is demonstrated in several materials including, LiNbO₃ as well as thin films of organic compounds like COANP and NPP. Associated mechanical factors contributing to modulation are also described.

Understanding the effects of chirp on the transmission of signals is of great importance to the system designer. Chirp can have two separate detrimental outcomes in a typical transmission system. The first is that the chirp can interact with the fiber dispersion to create a power penalty, which ultimately limits the number of channels or the distance over which the signal can propagate in today's WDM systems. The second is that chirp can broaden the transmitted spectrum limiting the channel spacing by interfering with adjacent channels even in a short-haul ultra-dense WDM environment. This paper covers time-resolved chirp measurements and the transient and adiabatic chirp properties of electro-absorption and directly modulated lasers. It also discusses methodologies to predict transmission path penalty from time-resolved chirp measurements.

Many devices using the electro-optic effect, in which the index of refraction changes upon application of an external electrical field, have been proposed to control the propagation of light in planar waveguides. Some electro-optic waveguides are made from polymers materials. However, none of them has the circular symmetry of optical fibers. Therefore the connection between optical fibers and planar waveguides is a difficult and costly task. A solution to this problem is to insert electro-optic polymers in a porous optical fiber. Such porous fibers are made of a plurality of interconnected micro-pores in a skeleton of silica glass and can be obtained from phase separation of alkali-borosilicate optical fibers. In this work, we describe porous optical fibers filled with a DR1-polyacrylate electro-optic polymer.

We have fabricated ultrafast electrical waveguides with low-k polyimide integrated with ultrafast photoconductive switches formed by nano-anodization process for the first time. Electrical signals are affected by nonlinear capacitance of p-n junctions in this waveguides, and pass through the low-k polyimide, so the dielectric loss and the radiation loss are dramatically reduced. The electrical pulses as short as 290 fs were measured on this waveguide by an electro-optic sampling system based on a femtosecond laser.

We have investigated the system performance of an experimental Praseodymium Doped Fibre Amplifier (PDFA) in an optical transmission system operating at 1.3μm. Experimental evaluation of the PDFA, based on Bit Error Rate (BER) measurements, is presented for the PDFA in copropagating and bidirectional configurations as a function of both wavelength and optical input power. The performance is analysed for both NRZ and RZ modulation format at a bitrate of 10 Gbit/s. The polarisation dependency of the PDFA is less than 0.2 dB. The results of an experimental analysis of the PDFA in an optical recirculating loop are shown for a NRZ modulated pseudo random data stream at 622 Mbit/s. A total span of approximately 2000 km is covered. Furthermore, the results of transmission experiments using the optical circulating loop at 10 Gbit/s are presented.

We study the impact of using on-chip forward error correction (FEC) in two-dimensional optical data link (2D-ODL) applications. We demonstrate that FEC can reduce the required launch power for a vertical-cavity surface-emitting laser (VCSEL), improve the reliability of 2D-ODLs, reduce on-chip power consumption and relax the requirements of the optical system. Both analytical and simulation results are presented to support our arguments.

Recent progress in thin film optical coating technology has enabled more complex filter designs and better control of out of band interference. One of the most significant advances in optical filters has been the manufacture of rugate filter designs based on sinusoidal variation of refractive index. The realization of a rugate filter requires a means of depositing an optical material whose refractive index can be significantly varied over a wide range, while having precise control of the index. The Glancing Angle Deposition (GLAD) technique satisfies these requirements by allowing fabrication of films with nano-engineered morphology whose optical properties can be tailored. GLAD is based on thin film physical vapor deposition by evaporation and employs oblique angle flux and substrate motion to allow nanometer scale control of structure and optical properties. Silicon rugate filter prototypes were made according to design specifications using computer control of deposition parameters which influence the film optical response.

We present a novel approach for the detection of leakage in oil pipelines using methods of fiber optic distributed sensors, a presence-of-oil based actuator, and Optical Time Domain Reflectometry (OTDR). While the basic concepts of our approach are well understood, the integration of the components into a complete system is a real world engineering design problem. Our focus has been on the development of the actuator design and testing using installed dark fiber. Initial results are promising, however environmental studies into the long term effects of exposure to the environment are still pending.

A modern challenge of materials science and physics is the creation and understanding of photonic crystals. Glancing Angle Deposition (GLAD) enables the growth of thin film materials with designable morphological structure on the scale of tens of nanometers, similar to proposed geometries of photonic crystals. Here we present recent progress toward the realization of photonic crystals with GLAD. Square spiral films of silicon were fabricated with GLAD, and were analyzed with scanning electron microscopy (SEM) and spectroscopic ellipsometry. The SEM images clearly show a periodic and spiral structure, similar to that recently predicted to have a robust three-dimensional bandgap. Ellipsometric analysis is ongoing, with as yet no distinct features that might suggest photonic bandgaps. To measure and control the in-plane ordering of silicon thin films, we have deposited and characterized pillar microstructures, producing an indirect measurement of film porosity with varying flux incidence. Two dimensional Fourier transforms were applied to plan view SEM images of porous pillar microstructures, showing no regular lattice but a broad ring that suggests a short range average spacing. In-plane periodicities were observed up to 100nm. Ongoing research is toward fabricating and analyzing photonic crystal structures at visible and infrared wavelengths.

By introducing microfluidic plugs into interior fiber microchannels, we have developed a new category of active, tunable optical fiber. The positions and optical properties of the fluidic plugs can be directly controlled by utilizing actuators and pumps located on the fiber surface, thereby allowing the propagation characteristics of certain optical fiber modes to be usefully adjusted. These hybrid microfluidic/silica waveguides preserve the advantages of conventional, passive optical fiber, while at the same time providing versatile tuning capabilities. Examples of variable narrow and broadband all-fiber filters are described here. These fluidic fiber devices have the potential to be important technologies for next generation optical networks.

The photoluminescence (PL) and thermoluminescence (TL) characterization of undoped and cerium and terbium doped nanocrystalline Y₃Al₅O₁₂ (YAG) prepared by the sol-gel method is reported. The experimental results of the PL show the typical emission bands centered at 490, 543 and 590 nm for YAG:Tb³⁺ and 530 nm for YAG:Ce³⁺ when excited with 325 and 345 nm light, respectively. The TL signal was obtained after exposure to UV-, X- and β- irradiation. The thermoluminescence results indicate that YAG:Tb³⁺ sample is very sensitive to all type of irradiation used, being highly sensitive for UV-irradiation. The high efficiency of the TL and PL suggests a good potential of this material as radiation dosimeter as well as active optical windows and new generation television screen.

Light emitting diodes operating in the near ultraviolet offer considerable advantage for adhesive curing in demanding applications, including flexibility of deployment, and uniformity of illumination. Wavelength limitations however must be considered when choosing LED curing solutions to ensure correct cure of adhesive for maximum performance.

In this paper we present preliminary results on a new type of optical material. By combining a thin reflective colloidal film with a superparamagnetic liquid known as a ferrofluid, it is possible to produce an optical quality surface that can be shaped by the application of a magnetic field. Ferrofluids are colloidal suspensions of nanometer-sized magnetic particles and are considered a well established, low-risk technology. We have demonstrated deformations of several microns at frequencies exceeding 100 Hz, making the material useful as a deformable mirror for adaptive optics and also of potential interest in numerous other optical devices. Liquid optics are relatively inexpensive when compared to conventional glass surfaces of similar quality and are free of mechanical constraints such as resonance and limits on the displacement of adjacent actuators. We present results to date and discuss some of the potential applications of liquid optics as well as the challenges remaining in realising practical devices based on this technology.

In this paper, tradeoff studies on several pixel level fusion algorithms and on their performance evaluation criteria are presented. Electro-optical (EO) and SAR sensors are dissimilar and produce images with very low degrees of correlation. These images are initially registered at subpixel level accuracy. The fusion is performed using the following pixel level fusion algorithms: Principal Component Analysis (PCA), Averaging (Ave), Laplacian Pyramid, Filter Subtract Decimate (FSD), Ratio Pyramid, Contrast Pyramid, Gradient Pyramid, Discrete Wavelet Transform (QWT), Shift Invariant DWT (SIDWT) with Haar, Morphological Pyramid, and the recent image fusion method developed by AUG Signals Ltd. A MATLAB based dedicated image fusion toolbox, that includes several pixel level fusion, restoration and registration algorithms, has been recently developed by AUG Signals. This toolbox is used for the tradeoff studies.

This paper presents the real-time observation of the Bragg grating formation in As₂S₃ channel waveguides. Channel waveguides (width~10μm) are obtained by a photolithographic process applied to a thin layer (~0.6μm) of thermally evaporated As₂S₃. The photoinduced variation of the refractive index is the principal mechanism involved in the formation of the Bragg grating. We used a typical holographic setup, with an Argon ion laser as recording source, to photoinduce gratings with Bragg wavelength ranging in telecommunication window. The time evolution of the transmission spectrum during illumination is also presented and analyzed here.

This paper presents experimental results on a 70-nm-wide, quasi-continuously tunable, single-longitudinal-mode erbium-doped fiber (EDF) laser. The cavity incorporates three tunable band-pass filters; a bulk grating based tunable band-pass filter, a fiber-ring-cavity filter, and an auto-tracking saturable absorption induced grating filter generated by an un-pumped EDF. In our experiment, this laser produced a single longitudinal mode oscillation between 1510 nm and 1580 nm, an output power of 0.5 mW and a tuning step of less than 0.2 pm. Optical frequency jitter was less than 0.8 pm and the signal to source spontaneous emission ratio (S/SSE) was higher than 60 dB. A tunable single-longitudinal-mode L-band fiber laser will also be discussed in this paper.

We report PMD effect on the distributed chromatic dispersion map measurement based on phase-mismatched four-wave mixing. The experimental results of distributed chromatic dispersion maps for a low-PMD dispersion-shifted fiber are described with spatial resolution of 250 m and dispersion accuracy less than ±0.02 ps/nm.km. For high-PMD DSF fibers, the chromatic dispersion map may be difficult to determine if the fiber has a long polarization-coupling length; however, it is still possible to be measured for a low polarization-coupling length fiber. Finally, the use of this method to determine distributed nonlinear coefficient will also be discussed.

The 970 nm radiation generated by a 4 W, 0.1 mm wide, InGaAs laser diode has been used to pump a Cr⁴⁺:YAG laser. With 3.3 W incident on the 10 mm long Cr:YAG crystal a maximum CW output of 90 mW has been obtained. Inserting a single plate birefringent tuner within the laser resonator permitted the laser wavelength to be tuned between 1380 and 1495 nm, with a peak output power of 11 mW at 1450 nm.

This paper describes the enabling technologies developed at INO to generate continuous surface-relief profile diffractive and refractive optical elements in photoresist. Grey-scale mask photolithography based on high-energy beam sensitive glass and laser direct writing have been used to fabricate aspherical refractive and diffractive microlenses respectively. Properties of refractive microlenses are compared to those fabricated by the standard reflow technique. The replication of such elements by injection molding and UV-embossing in acrylic and custom hybrid sol-gel glasses respectively is described. Fidelity of replication in the various processing steps is given. Optical performance of aspherical microlenses with f-numbers between 0.69 and 7 as well as thermo-mechanical properties of organic/inorganic materials are given.

There are many surface models that describe the comportment of photons when they hit a rough dielectric surface. However, the existing models did not give very good results when used to predict the photoelectron yields produced by BGO crystals. As those models use a slope distribution to describe the roughness of the surfaces, we have designed a new model using a height distribution rather than a slope distribution. MOSAIC uses a Delaunay triangulation to build a static surface. The staticity and the height variation of the surface should correct most of the problems that were not taken in account by a slope variation model such as shading and multiple reflections.

To date there have not been any direct measurements of winds in the Martian atmosphere. Measurements such as these are needed in order to understand the nature of the circulation and the transport of constituents in the atmosphere of this planet. In this paper, a conceptual design for a small visible/near-IR imaging interferometer capable of fulfilling this need is described. The design is based on a similar successful instrument, the Wind Imaging Interferometer (WINDII), which flew in Earth orbit. The basic measurement set includes Doppler shifts (from which wind is derived), rotational temperatures, line widths and radiances of isolated lines in the O₂(α¹Δ_g) band airglow and O(¹S) airglow emission. The design challenges which were met in converting an instrument designed for terrestrial applications to one capable of flying to Mars and operating in conditions there include reducing the mass and power requirements and adapting the instrument to appropriate data rate and S/N requirements. The resulting instrument has a mass of approximately 15 kg, requires on average, 10 Watts of power and has a data rate of 32Mbits/day. In this paper the design of this instrument and how it accommodates the particular requirements of a Mars mission are described.

The state of polarization (SOP) is measured in various field optical fibers. A biased probability density is found. This is contrary to the generally accepted uniform probability density. A Maxwellian probability density function (PDF) for differential group delay (DGD) at a fixed wavelength will thus not occur when measured on these fibers for a median time period. Long term PMD measurements result in a quasi-Gaussian polarization mode dispersion (PMD) PDF when using an interferometric test-set. However, it is found that the interferometric quasi-Gaussian mean value corresponds to the mean value of the accepted Maxwellian PDF.

We have performed an experiment in a chalcogenide thin film that is questionning some aspects of the currently accepted phenomenological model for the photoinduced anisotropy in such material. By analyzing the kinetics of the photoinduced linear dichroism, we were able to explain our experimental results by revisiting the current model which is based on anisotropic microstructures. This model is modified to include disk-shaped polarizability tensor. The approach we present is a useful tool to extract information on the optical properties of microscopic structures based on a macroscopic phenomenon.

In the present work, we study the polarization properties of obtained diffraction gratings. A strong anisotropy was observed while monitoring diffraction efficicency during recording of the gratings. Angular selectivity studies for different incident polarizations will provide us important information on the LC molecules and droplet orientation.

A three-dimensional (3D) colloidal crystal have been grown from an aqueous colloidal solution of highly monodisperse submicrometer-sized polystyrene spheres using a self-assembly processing technique. The electromagnetic waves diffracted by this crystal can interfere and give rise to a photonic band-gap. However, due to the low refractive index contrast within this material the band-gap is incomplete. By filling the voids between the spheres of the colloidal crystal with titania and removing the polystyrene beads by sublimation, we obtained an inverse-opal structure with an increased refractive index contrast showing strong opalescence.

We report results from a systematic study of the linear refractive index of thin films made of As-S-Se glasses which are part of the chalcogenide family. We have studied eight different compositions. The refractive index are measured by the mean of a grating coupling experiment. The measurements are performed around 1.5μm for both annealed and non-annealed glasses. We observe that annealing the samples increases their refractive index. We also note that the increase of Selenium concentration increases the refractive index and the decrease of Arsenic concentration decreases the refractive index.

We show, through second order moment theory, the existence of a new regime of self-similar chirped-solitary wave in an appropriately dispersion-profiled fibre. This study completes the concept of quasi-solitons introduced by Kumar and Hasegawa. Theory reveals the existence of an invariant relation respected by quasi-solitons. This invariant relation can be fully recovered by the usual variational approach of the non-linear Schroedinger equation (NLS) and it can be used to study non-linear pulse propagation in constant dispersion optical fibers and ultimately for dispersion management. The work has been carried out for the lossless as well as for the lossy case.

PMD measurement results and theory of a single waveplate are presented. A commercially available waveplate is meas-ured, using a new instrument that allows one to distinguish the intrinsic PMD of the waveplate material from mixed effects, and to retrieve the relevant parameters through multi-resolution analysis. This illustrates, in the most simple case, a generally unexpected PMD behavior that can be observed in multipath optical components. Emphasis is put on the basic need to carefully choose, or at least specify, the resolution bandwidth of PMD measurements. This proves necessary not only to understand the results, but also to characterize PMD-induced pulse spreading.

A polarization additive pulse mode-locked stretched-pulse erbium-doped fiber ring laser with a regenerative feedback producing near transform-limited femtosecond pulses is reported. The regenerative feedback makes use of an intensity modulator driven at twice the fundamental repetition rate of the passively mode-locked fiber laser. The laser is self-starting for a limited range of pump power. The de-chirped pulses have a duration of 90 fs (FWHM) and a pulse time-bandwidth product of 0.44. The pulse energy amounts to 0.3 nJ. Pulses with nearly twice that energy could be obtained, though without self-starting capability. The laser RF power spectrum measurement yields an amplitude noise as low as 0.15% (rms) and a pulse timing jitter of 150 fs (rms). In addition, RF spectra show no relaxation oscillation in the self-starting regime.

Experimental studies on laser driven high-speed metallic flyers have been carried out wiht a moderate Q-switched YAG laser whose output is 1J and pulse FWHM of 10 ns. An aluminum film of thickness 5.5 micrometers was accelerated to a speed about 7 km/s. The experiments on initiation of explosives and spallation of metals were performed using laser driven flyer. A numerical model is explored here for a description of vaporization, ablation and ionization during the laser irradiation and can give reasonable results compared with the experiments.

To understand the biology of living cells, such as the neurons in our brain, we focus on the molecular signaling interactions that proteins perform intracellularly. We have been studying the behavior of an enzyme, termed 'CaMKII', inside living neurons maintained in tissue culture. This enzyme plays a critical role in the control of synaptic transmission. Such role may involve the dynamic translocation of the enzyme at synaptic sites upon specific stimuli. To study this translocation, we use a cellular imaging technique that allows us to monitor the movement and targeting of CaMKII tagged by genetic engineering with a green fluorescent protein (GFP). We find that the enzyme translocates within seconds to synapses upon synaptic activation by neurotransmitter application. Our approach has lead to several key findings on the regulation of CaMKII translocation to the synapse and on its potential role in synaptic plasticity. However, several new advances in photonics and image analysis, which we will implement in our laboratory, will greatly help pushing the limits of our resolution of such type molecular event in living cells.

TM_op free-space laser beams (radially polarized and transverse magnetic Laguerre-Gauss beams) have an on-axis longitudinal electric field that has the prerequisites needed to achieve up-to-GeV electron acceleration in a diffraction-limited interaction. We describe how highly relativistic electrons can be synchronously accelerated. Under extreme conditions the energy gain experienced by the accelerated electrons can be well in the multi-GeV range.

Excellent electro-optic properties of SBN crystals explain the attempts to control the deposition of high ordered SBN thin films with the aim of optical waveguiding and processing integration. We have reported in this paper the first epitaxial growth of SBN on MgO substrates using a sputtering method. The SBN stoichiometry approach and single phase preparation have been shown to be possible on the basis of the deposition mechanisms analysis. In spite of the XRD unreliability as an experimental guide in the complex case of SBN growth, the occurrence of a strong orientation of the SN parasite phase on MgO is shown to provide an efficient XRD test of the stoichiometry approach. Epitaxial SBN thin films are obtained which exhibit two in-plane orientations mirror symmetric to the MgO cell axis.

We introduce a new version of DETECT. DETECT is a Monte-Carlo simulator developed for the Computer Aided Design (CAD) of optical photon sensing devices. The simulator generates individual emission photons in specified locations of a photon-emitting device and tracks their passage and interactions in active and passive components of the system. Extensive options are available in the simulator to model the geometry of the photon sensing device, to account for the time and wavelength distribution of emission photons, to track their interactions with surfaces, to account for their possible absorption and re-emission by a wave-shifting components and to model their detection by pixelated photomultipliers or photodiodes. DETECT2000 is a very significant upgrade of DETECT97, which has long been established in the nuclear medicine instrumentation community for its accuracy to model the performances of high resolution energy and position sensitive gamma-ray detectors. The 2000 version of DETECT offers an accelerated version of the simulator which has been redesigned in the object-oriented C++ language. New features such as the tracking of the time and wavelength history of individual optical photons have been added.

Thermo-optic layers of thin film semiconductors are deposited by PEVCD to create thermally tunable bandpass filters for WDM optical networks. Amorphous semiconductor films, adapted from the solar cell and display industries, are the primary ingredient. Single-cavity tunable filters with FWHM=0.085 nm, >40 nm tuning range, and insertion losses 0.2-4 dB are demonstrated. Key enablers for this new family of index-tunable thin film devices are PECVD deposition, large internal temperature changes >400C, high conductivity polysilicon heater films, and extremely robust film adhesion. Possible applications include optical monitoring, add/drop multiplexing, dynamic gain equalization, and dispersion compensation.

An in-line Fraunhofer holographic system which can measure the size distribution and the mass of particles ejected from a target surface at speeds up to 5.0 km/s is described. Observed particle diameters range from 4μm to several hudnreds μm, and teh depth of field is 10mm to 15mm. In order to avoid damage of the hologram, an optical relay system is used to relay the interference pattern 90cm. After the hologram has been made a spatially filtered laser is used to reconstruct a real image of particles over a 3D volume. Then the real particle images from the 3D volume are digitized via a CCD camera with 1280×1024 pixels. We have used this system to measure static or slow moving particle field, the experimental results show that the system's performance are very good.

Reconstructed silica made from porous glass is used to fabricate doped multimode optical fibres. This process constitutes an alternative to the more classical Modified Chemical Vapour Deposition (MCVD) process when used in conjunction with solution doping. Comparison between porous glass and porous silica soot obtained from MCVD allows to highlight the advantages and disadvantages of both methods. The reconstructed glass process has been used to develop a multimode high attenuation optical fibre (HAF) working at 850nm.

The concept of intensity ratio alignment technique will be introduced by comparing it with the conventional null technique. For in situ/real time monitoring the plasma etching process, we will introduce a fixed incident angle alignment technique for a photoelastic modulation ellipsometer. In addition to ellipsometry, we will introduce a photoelastic modulation polarimetry to measure the twisted angle and phase retardation of a twisted nematic liquid.

In this paper, the design and applications of Large Scale Integrated (LSI) Planar Lightwave Circuits (PLCs) for WDM systems are discussed. The general design issues of PLCs', such as size, loss and crosstalk are addressed. A 32-wavelength optical add/drop multiplexer (OADM) with 4 pairs of fully addressable add/drop ports is presented as an example application for LSI-PLCs.

Since the beginning of optical fiber communications, many fiber designs, driven by the desire to extend the fiber limited performances, have been proposed. In the last decade, the most innovative concept that came out is probably the HF (Holey Fibre). This new fiber design consist of a pure silica fiber with a periodic array of air holes running along the length of the fiber. Usually, the air holes forming the cladding region are arranged in an hexagonal lattice and the introduction of a defect, absence of a hole, in the center of this periodic structure creates the core of the fiber. Over the past few years, impressive possibilities offered by this new type of fiber have been demonstrated in various fields of optical fiber technology such as single-mode fiber, high optical power guidance, polarization control, dispersion compensation, soliton propagation, continuum generation, fiber lasers and amplifiers, remote sensing, etc. In this paper, we review the technology and present our design, fabrication capability, as well as some results obtained with our HFs.

We have given designs of a Small Residual Dispersion Fiber (SRDF) and a corresponding Dispersion Compensating Fiber (DCF), where the dispersion slopes of these fibers are so adjusted that a small length of the DCF will approximately compensate the accumulated dispersion in SRDF simultaneously at all wavelengths in the range of 1530 to 1565 nm (gain window of Erbium Doped Fiber Amplifiers). The maximum values of the effective dispersion and the slope of the effective dispersion in the wavelength range of 1530 to 1565 nm are approximately 0.08 ps/(km.nm) and approximately 0.01 ps/(km.nm2), respectively.

In this paper the results of the numerical investigations for different modulation formats in 40 Gb/s based WDM transmission systems over standard single mode fiber (SSMF) are present. The aim of our works was a precise investigation of the transmission behavior of 40 Gb/s WDM systems considering different modulation formats in linear and nonlinear transmission regime. Thereby the maximum achievable spectral efficiency for each modulation format has been analysed.

Semiconductor optical amplifiers (SOA) have been received more and more attention as the rapid development of all-optical switching and optical access network. In this paper some key technologies about SOA are described and the potential applications of SOA are outlined

In this paper two applications of photonic technologies for visual implants in the field of medicine are presented. Both are technical systems working as vision aid for people suffering from blindness due to damages in their visual system. The first system is a retinal implant (RI), the second an intraocular vision aid (IoVA) for people with opaque cornea.

We show that, in addition to a stable single soliton, a dispersion-managed system can also support stable bi-solitons. The system parameters in which the bi-solitons can exist are also studied. In addition, we propose novel error preventable line-coding schemes in which binary data are assigned to bi-solitons and single dispersion-managed solitons. By using the schemes, impairments arising from intra-channel interactions can be drastically reduced compared with the conventional scheme for the same bit rate.

A comparison is made between three high spatial resolution index of refraction profiling techniques:reflection-NSOM, microreflection and AFM plus selective chemical etching using the very small elliptical core of a polarization maintaining E-fiber from Andrew Corporation as a test waveguide.

Carrier dynamics in InAs/GaAs self-assembled quantum dots have been studied by using time-resolved photoluminescence experiment. We have studied a series of doped quantum dot structures by looking at the role of the experimental conditions, such as the laser excitation intensity, the crystal temperature and the intersublevel energy, on the carrier relaxation time. For all samples, we have found two distinct relaxation regimes. At a crystal temperature of 77K, a rise time of the quantum dot emission signal of a few tens of ps has been measured under low photocarrier densities. This rise time decreases significantly, down to few ps, as the laser intensity increases. These results show that carrier-carrier scattering processes play a significant role at high photo-excited carrier densities. Under the low-excitation regime, the dot emission rise time depends on the dopant type, on the doping level on the degree of intermixing and on the temperature. Our results obtained on structures having a relatively low density of dots indicate that transport processes (diffusion and localization at the InAs/GaAs interfaces) limit the dot capture efficiency at low temperatures. The experimental conditions and the dot structural parameters that give rise to ultrafast capture and intra-dot relaxation times are discussed.

In the present work, electric field distribution of an InGaAs/InP PIN mesa type photodetector is studied by employing electron beam induced current (EBIC) technique using a scanning electron microscope (SEM) with consideration of electron-hole pair generation volume. Depletion width and p⁺/n^- metallurgical junction location are determined in the experiment.

We present theoretical and experimental results for the generation of both transmission-line-coupled terahertz electrical transients and free-space terahertz radiation. Time-resolved reflectivity experiments are used to gain insight into the ultrafast carrier dynamics and fundamental limitations of conventional photoconductive (PC) switches. Self-switching and frozen wave generation are introduced as effective sources of terahertz electrical transients, and the PC response of these techniques is seen to be independent of the charge carrier lifetime in the semiconductor substrate. The concept of PC switching is further extended to the launching of free-space terahertz radiation, and electro-optic sampling techniques using polycrystalline sensors are shown to be viable sensors for free-space terahertz radiation.

The formation of dual gratings is investigated with the isotropic UV curable epoxy resin Ebecryl 600 with the photoinitiator Darocur 1173. The diffraction patterns are discussed in the simple crosslinking model and the formation of relief patterns is investigated. Furthermore the phase relation between the relief pattern and the light pattern is determined using asymmetric patterns.