This PDF file contains the front matter associated with SPIE Proceedings Volume 6890, including the Title Page, Copyright information, Table of Contents, and the Conference Committee listing

Visible lasers and amplifiers have potential applications in the fields of optical data storage, spectroscopy, biomedical and optical local area networks. In this study, Tb³⁺-Yb³⁺ co-doped fluorophosphate glasses were synthesized and properties of the visible emission at 0.54 µm were investigated. A upconversion excitation efficiency from Yb³⁺ to Tb³⁺ was studied by evaluations of a cooperative energy transfer efficiency from Yb³⁺ to Tb³⁺ (ηCET) and a back-transfer efficiency from Tb³⁺ to Yb³⁺ (ηBT ) which give positive and negative contribution to upconversion excitation, respectively. The ηCET was as high as 25 %, and the ηBT was less than 1 % in the fluorophosphate glass. This indicates that Tb³⁺-Yb³⁺ co-doped fluorophosphate glass is promising as new laser and gain media in the 0.54 μm band.

In this work we report the infrared to visible upconversion luminescence in Er³⁺-doped ZrO₂-CaO eutectic crystals with an ordered microstructure. The microstructure consists of alternating 2 μm thick lamellae of calcia-stabilized zirconia (CaSZ) and CaZrO₃ crystals. Er³⁺ ions enter both phases but at a higher concentration in CaSZ. Site selective excitation at different wavelengths along the ⁴I_15/2→⁴I_9/2 absorption band allows to select the upconverted emission from Er³⁺ ions corresponding to the two components of the eutectic samples. Depending on the excitation wavelength the upconversion emission spectrum is dominated either by the CaZrO₃ contribution, with an intense green emission characterized by sharp peaks from (²H_11/2,⁴S_3/2) levels together with a more weak red emission from ⁴F_9/2 level, or by the CaSZ phase with broad green and red emissions with an enhancement of the red emission from level ⁴F_9/2. The possible upconversion mechanisms are discussed in terms of excitation power dependence and lifetimes of the upconversion emissions.

Luminescent thin films are used for many applications, including light-emitting diodes, lasers and flat panel displays. Glancing angle deposition (GLAD) is a physical vapor deposition technique which relies on highly oblique flux angles to create porous thin films. When combined with real-time substrate motion control and measurement of deposition rates, it is possible to produce high quality nanostructered thin films. A rugate filter uses a sinusoidally varying index profile to produce a stop band. Using the GLAD technique, it is possible to produce a rugate filter from a single material. The central wavelength, depth and width of the stop band can be designed by adjusting the film nanostructure. In this paper, rugates composed of Y₂O₃:Eu are used to control the angular emission profiles of the photoluminescent thin film. Confined, annular and isotropic emission profiles film is nearly uniform for emission angles between ~ -60° and ~60°.

We review the advanced attributes of double-clad optical fibers made by the Yb/Al-vapor-doped OVD (outside-vapor-deposition) method developed at Corning Incorporated. The method is characteristically completely synthetic in nature, which allows fiber composition flexibility for both the core and the claddings. Consequently, it has enabled some highly desirable fiber features, such as low-NA core (< 0.05), high-NA clad (> 0.32), high Yb-doping concentration (> 1.2wt %) and ultra-low passive background-loss (~1/~3dB/km for core/innerclad @1310nm), in addition to the unique all-glass double-clad structure by additional composition engineering for the outerclad. Further, a high performance SBS-mitigated double-clad fiber is presented as an example enabled by this versatile OVD methodology.

Hot embossing of novel inorganic-compound glasses is a new fabrication technology for guided wave devices and circuitry. A patterned mould is pressed into the glass above its glass transition temperature (T_g) and replicated; cooling below T_g freezes-in the required pattern. The state-of-the-art is reviewed. Better than 0.1 μm -scale replication is shown for chalcogenide glasses and fabrication of a hot embossed monomode waveguide demonstrated.

μA simple method based on the sol-gel technology has been developed to coat passive microspheres with an active coating. The microspheres were prepared by fusion of a standard telecom fiber with a dimension of about 200 μm and 400 μm and have been respectively dipped in a 70SiO₂-30HfO₂ sol activated by 1 mol% and 0.1 mol% of erbium ions. Here we first report about the luminescence properties of a silica-hafnia coating doped with erbium ions and then whispering gallery mode spectra were analysed for different sphere diameters, thickness of coating and erbium concentration. The thickness of the coating has been chosen in order to support at least one whispering gallery mode at 1.5 μm.

Tellurite glass micro-superspheres (Te-μSSs) were prepared by the surface-tension mold (StM) technique, and their whispering gallery mode (WGM) resonances have been investigated as the first trial to realize an ultra-broadband Raman resonator. Micrometer-sized tellurite glass particles were melted on an optical grade glassy-carbon substrate then cooled to room temperature (StM technique). Resultant Te-μSS possesses a super-spherical shape with high optical transparency. The size of the partly truncated area, resulting from the contact surface with the substrate, can be controlled by the composition of the glass and a microsphere with no truncated area was achieved for a glass with 56TeO₂-3.5BaO-10.5SrO-8Nb₂O₅-4WO₃-16P₂O₅ (TBSN-4W-16P) composition. The TBSN-4W-16P μSS was excited at 532 nm, and the WGM resonance emission attributed to broad Raman scattering of the glass itself was observed. The Q value of the μSS was ≈ 5 × 10³. It was confirmed that the prepared μSSs possess a sufficiently spherical shape and acted as an efficient WGM resonator. These results predict that the Te-μSS has potential for a novel broadband Raman laser.

Narrow-band filters based on phase shifted Bragg gratings have been widely investigated in fiber configuration. However, up to now, no experimental demonstration was performed using volume Bragg gratings in free space configuration. In this paper both theoretical and experimental study of this new type of filters is presented. The phase matching conditions that allow obtaining a resonant filter are analyzed. Narrow bandwidth transmission filters based on the coherent combination of two non slanted reflecting Bragg gratings in photo-thermo-refractive glass are studied. A filter with 25 pm bandwidth and 90%+ transmission at 1064 nm is demonstrated. The effect of the phase matching between the two volume Bragg gratings is presented and perfect accordance of experimental and theoretical data are shown. Based on these results, we show that the phase-shifted reflecting volume Bragg gratings recorded photo-thermo-refractive glass pave a way to the fabrication of large aperture extremely narrow band filters with high transmission at resonance and high rejection.

We present a new design of high sensitivity, multi-spectral capability AlGaAsSb/InGaAsSb phototransistors for infrared sensing and solar energy conversion applications. These devices are grown by molecular beam epitaxy (MBE), which exhibit high responsivity at room-temperature. The 50% cutoff wavelength of spectral photoresponse is 2.2 μm. Similar structures are also investigated for solar cell applications. The possibility of increasing the solar energy conversion is explored by incorporating nano-antenna array into the solar cell. The broad-band nano-antenna is designed using Ansoft HFSS. The results indicate high solar energy conversion can be achieved for highly efficiency, flexible, lightweight solar power generations for the applications such as aircraft, airbase and special operations.

The fabrication of microchannel plate (MCP) with bulk-conductive characteristics has been studied. Semiconducting clad glass and leachable core glass were used for drawing fibers and making MCP. Co-axial single fiber was drawn from a platinum double-crucible in an automatic fiberizing system, and the fibers were stacked and redrawn into multifiber by a special gripping mechanism. The multifibers were stacked again and the boule was made and sliced into discs. New MCPs were made after chemically leaching process without the traditional hydrogen firing. It was shown that bulk-conductive glass MCP can operate at higher voltage with lower noise.

Silicon Readout Integrated Circuits (ROIC) for HgCdTe Focal Plane Arrays of 1×4 and 72×4 photovoltaic detectors are represented. The analog circuit blocks are completely identical for both, while the digital control circuit is modified to take into account the larger array size. The manufacturing technology is 0.35μm, double poly-Si, three-metal CMOS process. ROIC structure includes four elements TDI functioning with a super sampling rate of 3, bidirectional scanning, dead pixel de-selection, automatic gain adjustment in response to pixel deselection besides programmable four gain setting (up to 2.58pC storage), and programmable integration time. ROIC has four outputs with a dynamic range of 2.8V (from 1.2V to 4V) for an output load of 10pF capacitive in parallel with 1MΩ resistance, and operates at a clock frequency of 5 MHz. The input referred noise is less than 1037 μV with 460 fF integration capacitor, corresponding to 2978 electrons.

Spectral Domain Optical Coherence Tomography (SD-OCT) is a rapidly growing imaging technique for high-resolution visualization of structures within strongly scattering media. It is being used to create 2-D and 3-D images in biological tissues to measure structures in the eye, image abnormal growths in organ tissue, and to assess the health of arterial walls. The ability to image to depths of several millimeters with resolutions better than 5 microns has driven the need to maximize the image depth, while also increasing the imaging speed. Researchers are using short-wave-infrared light wavelengths from 1 to 1.6 microns to penetrate deeper in denser tissue than visible or NIR wavelengths. This, in turn, has created the need to increase the line rates of InGaAs linear array cameras by a factor of ten, while also increasing gain and reducing dead time. This paper will describe the development and characterization of a 1024 pixel linear array with 25 micron pitch and readout rate of over 45,000 lines per second and the resulting camera. This camera will also have application for machine vision inspection of hot glass globs, for sorting of fast moving agricultural materials and for quality control of pharmaceutical products.

Bi-doped glass optical fibers are a very promising active laser medium. Luminescence of Bi-doped glasses takes place in a spectral region of 1100-1500 nm [2], where no fiber lasers (or any other efficient lasers) exist. The glasses have very broad luminescence bands (200-400 nm) and long lifetime (200-700 μs). The Bi absorption bands are situated in a spectral region of 500-1100 nm where long-lived high-brightness laser diodes developed for the pumping of lasers and amplifiers are available. Besides, strong luminescence has been observed in a variety of glass compositions. However, up to 2005 there had been no reports on the fabrication of Bi-doped optical fibers. The first Bi-doped optical fibers were fabricated in 2005 [5,6] and that year the first Bi-doped fiber laser was constructed [7]. In this paper the recent results on the new laser material - Bi-doped glasses and optical fibers are reviewed. First, luminescence properties of various Bi-doped glasses are discussed. Then we describe the Bi-doped silica-based optical fiber fabrication by MCVD technique and the absorption and luminescence properties of the fibers. At last the results of investigations of high-power Bi-doped fiber lasers are presented.

We report for the first time, to the best of our knowledge, 304 mW green light emission generated by frequency doubling of the output from a 1060-nm DBR semiconductor laser using a periodically poled MgO-doped lithium niobate waveguide in a compact single-pass configuration. The excellent performance of these DBR lasers, including a kink-free power greater than 750 mW, single-spatial-mode output beam, single-wavelength emission spectra, and high wavelength-tuning efficiency, plays an important role in the generation of high-power green light.

Power scaling of nanosecond fiber laser pulses with narrow linewidth has been demonstrated by using a new single-mode (SM) large-core polarization maintaining (PM) highly Er/Yb co-doped phosphate glass fiber (EYPhF). We used an optimized length of 12 cm of the EYPhF fiber in the power amplifier of the all-fiber MOPA chain. The pulse energy can reach 0.11 mJ for the amplified pulsed fiber laser, which corresponds to a peak power of 51.5 KW with pulse duration of 2.1 ns and repetition rate of 5 KHz. This high power pulsed fiber laser has an estimated linewidth of < 500 MHz.

White light was produced exploiting additive synthesis of red, green, and blue(RGB) fluorescence generated through frequency upconversion in fluorogermanate glass samples co-doped with Ho³⁺, Tm³⁺ and Yb³⁺, and excited by a single source of near-infrared radiation. The blue(475 nm), green(540 nm), and red(650 nm), upconversion luminescence signals were, respectively, assigned to thulium(¹G₄ - ³H₆), and holmium(⁵S₂;⁵F₄) → ⁵I₈, ⁵F₅ → ⁵I₈) ions, both excited via successive energy-transfers from ytterbium ions. The Tm³⁺, Ho³⁺, and Yb³⁺ concentrations in the glass host were adjusted yielding the emission of a wide color gamut in the visible spectrum, and the production of white light using a single infrared source of excitation at 975 nm.

We are advancing the development of ultrahigh-speed, high-sensitivity CCDs for broadcast use that are capable of capturing smooth slow-motion videos in vivid colors even where lighting is limited, such as at professional baseball games played at night. We have already developed a 300,000 pixel, ultrahigh-speed CCD, and a single CCD color camera that has been used for sports broadcasts and science programs using this CCD. However, there are cases where even higher sensitivity is required, such as when using a telephoto lens during a baseball broadcast or a high-magnification microscope during science programs. This paper provides a summary of our experimental development aimed at further increasing the sensitivity of CCDs using the light-collecting effects of a microlens array.

Single-photon avalanche photodiodes (SPADs) based on an improved structure were fabricated. Measurement results show that SPADs with a sharp rising I-V and gain curves were obtained by controlling SPAD's multiplication region thickness. The tunneling leakage current was reduced. Device's dark count rates (DCR) and single photon detection efficiency (SPDE) were measured using our innovative gated current bias scheme under different operating conditions to obtain a maximum SPDE. The experimental data demonstrated that SPADs' performance can be improved by decreasing the difference between the breakdown voltage and the punch through voltage.

The samples were prepared from CdZnTe substrate with thickness of 600µm, on wich thin CdHgTe (KRT) thin films with thicknesses of 16µm, 18.75 µm and the same sample with KRT thin film with thickness 21.6µm was coated by diamond thin film with thickness of 30nm. B ion implantation into KRT film on CdZnTe substrate was made with purpose of investigation of volt-ampere characteristics and defects formation. Ion doping of B in KRT with doses of (D=3.4 mCl/cm2, D=6.8 mCl/cm2) and energies (50 keV, 100 keV, 150 keV). The calculations by SRIM-TRIM 2003 software for condition of maximum ion distribution on the interface "filmsubstrate" have shown that the optimal energy is 100 keV for all mentioned samples. The results also have shown that implantation at ions energy 100 keV is optimal for form diode p-n structures in narrow(-band)-gap semiconductor material CdHgTe/CdZnTe.

At the present time, silicon and InGaAs/InP photodetectors from different manufactures have rather low level of noise, a good uniformity of the surface response as well as a wide dynamic range and linearity. For these reasons they are exploited in the instruments for measuring optical radiation within the near infrared range 800-1600 nm. Furthermore, the silicon and InGaAs/InP photodetectors are used for maintaining the scales of spectral responsitivity in the above-listed spectral range in many laboratories. Due to the last application, we presented our studies of the reflectance and the internal quantum efficiency inherent in silicon and InGaAs/InP photodiodes from different manufactures. Both the reflectance and the internal quantum efficiency determine the photodiode spectral responsivity, which is the radiometric characteristic of interest in the fields where these devices can be used for optical radiation measurements. The responsivity will be known if both the reflectance and the internal quantum efficiency are known at every wavelength We have measured the reflectance of three silicon photodiodes and three InGaAs/InP photodiodes that were practically used to maintain scale of the spectral responsivity in the Institute for Applied Physics (CSIC). The results obtained show that we have an outstanding change between the reflectance of the photodiodes of the same set, which indicates that its necessary to measure the reflectance of every individual photodiode if an accurate reflectance knowledge is needed, its necessary to measure the reflectance of every individual photodiode to have a precise knowledge on the evolution of its reflectance.

Thin-film CdS was deposited onto glass with nanosecond pulsed-laser (PLD) deposition using 355 nm for only 2 minutes resulting in a 200 nm thick film. X-ray analysis revealed a peculiar texture consisting of crystallites embedded in an amorphous matrix. Employing alternating and constant light sources, i.e., chopped light and a light emitting diode (LED) in conjunction with lock-in technique, we introduce here a straightforward way to modulate the alternating responsivity (AR) of the CdS film at room temperature. The arrangement was the following: Aluminum contacts were evaporated on the film surface and were electrically connected to a power supply and a lock-in amplifier. The chopped light was exciting the film surface between the contacts and a blue (465 nm) LED was directed to the same area. In this way, it was possible to measure the AR of the film under the influence of blue background irradiation. Notably, the efficiency of the bleaching effect depends on the applied electric field, intensity of blue LED and chopped photon energy. Around 50% quenching is observed at 100 V/cm in the vicinity of CdS band gap. The per cent quenching is decreased with increase in bias and increase with increase in the blue LED intensity. The modulation is attributed to the shortening of the available AR carriers due to the generation of direct current channels in the film. Summarizing, the work demonstrates the use of the lock-in principle for modulation and quenching techniques in optoelectronics rather than for applications in metrology only.

All-optical 4-bit Gray code to binary coded decimal (BCD) converter was demonstrated, for the first time in our knowledge, with the number of 12 SOAs by means of commercially available numerical analysis tool (VPI). Circuit design approach was modified appropriately in order to fit the electrical method on an all-optical logic circuit based on cross gain modulation (XGM) process so that signal degradation due to the non-ideal optical logic gates can be minimized. In our approach, only using XGM process as a nonlinear function, the maximum number of XGM process serially underwent by input signals is twice at the most insuring signal quality. Without regenerations, Q-factor of around 4 was obtained for the most severely degraded output bit (least significant bit - LSB) with 2.5Gbps clean input signals having 20dB extinction ratio. It is worth to note that, implementing this LSB is complex enough to give it as an example of a 4-bit conversion system. While modifying two-level simplification method and Karnaugh map method to design Gray code to BCD converter, general design concept was also founded in this research not only for the Gray code to BCD converter but also for any general applications such as encoder / decoder, multiplexer / demultiplexer, and read only memory so that readers can develop their own all-optical logic device easily using XGM process in SOAs.

A novel TiO/NiO multilayer mirror based on an atomic layer epitaxy (ALE) technique has been designed to realize a high reflective mirror and an attosecond chirped mirror in soft x-rays "water-window" wavelengths region. The layer thickness should be controlled on an atomic scale, but in ALE, according to a self-limiting mechanism which is found in the fabrication of oxide thin films, the epitaxial growth is automatically stopped at strictly 1 monolayer (ML) in one alternative precursor dosing. An oxide multilayer is also expected to overcome serious problems such as scattering loss at interfaces of the multilayer. TiO and NiO are an exquisite combination which has the potential to make their superlattice on a MgO substrate because each oxide has the NaCl structure of nearly equal lattice constant (TiO = 0.41766 nm, NiO = 0.41684 nm, MgO = 0.42112 nm). The theoretical calculation of a periodic multilayer mirror showed the high reflectivity of over 50% at a wavelength of 2.73 nm and the incident angle of 18.9° from the normal incidence. Additionary, reflective properties of ultrashort pulses induced to design a chirped structure stacked by blocks of several multi-periodic structures, which must have a spectral bandwidth and a controlled phase to compress a temporal broadening of the pulses down to a few hundreds of attoseconds. In this paper, we report the details of structures between titanium oxide and nickel oxide, and properties both as a high reflection mirror and as a chirped mirror.

We have designed, assembled and tested a phase-array antenna using fiber Bragg gratings in the highly dispersive transmission region as our tunable true-time delay (TTD) generators. The TTD generator is designed by cascading 29 identical fiber gratings and 1×2 fiber splitter pairs. Tapping from each fiber splitter allows us to steer our RF microwave beam from a 30×4-element antenna by tuning the wavelength of a laser. The 10Ghz RF signal is superimposed upon a laser beam by means of a LiNbO₃ modulator. However, with a conventional modulator, the optical frequency spectrum of the modulated beam consists of two sidebands on opposite sides of the optical carrier; all three of which may experience very different time delays due to dispersion. This may have detrimental effects on time-delay sensitive processes such as antenna beamforming. Therefore, we studied the use of single-sideband versus double-sideband modulators in the transmitters of photonic phased array antenna. We focus in particular on the effect of the different spectral profiles of single and double sideband modulators on beamforming when using the fiber Bragg gratings as TTD generators. With very high dispersion in our fiber Bragg gratings close to the band edge, the absolute propagation times are different for each sideband and the optical carrier. Therefore double sideband modulated signals will generate two sets of separate delays in the same microwave signal which causes beam deterioration and increased side-lobes. We demonstrated this theoretically and verified experimentally by comparing the antenna patterns generated by single-side-band and by double sideband modulators.

We propose the holey-fiber-based optical cord cables with the excellent optical characteristics in terms of attenuation loss, insertion loss, and bending loss for the application to access network like FTTH. The attenuation loss of the holey-fiber- based cord cable with the length of 1 km at 1383 nm is as low as ~0.323 dB/km. The bending loss under the bending diameter of 5.5 mm is measured to be ~0.04 dB. We also test the proposed holey-fiber-based optical cable for E-PON transmission systems by measuring the internet speed in the server under the bending diameter of 7, 3, and 1 cm.

We demonstrate a 22 dB all-fiber amplifier at 546 nm using Er³⁺-doped fluoride fiber by forward upconversion pumping of a 974 nm laser diode. The gain saturation effects and the power conversion efficiency of this amplifier are investigated in detail based on gain characteristics and numerical simulations.

An oblique metal island (OMI) film is composed of prolate metal nanoclusters inclining to one side. The OMI film has large optical anisotropy as the resonance wavelengths for the polarization along the shorter and longer axes of the prolate metal nanoclusters are different from each other. Therefore, the multiplayer of the OMI layers and thin glass layer could be used as an optical polarizing film. In previous works, we have investigated the optical polarizing films using ideal OMI films with uniform aspect ratio of islands for simplification. However, in the OMI films fabricated by using a conventional vacuum evaporation system, the aspect ratio is not uniform. In this paper, we describe the optical polarizing film using the OMI films with distributed island shape. We have calculated the optical characteristics of the OMI films with distributed island shape by assuming that the distribution of aspect ratio of islands is expressed by use of the log-normal function. As the variance of aspect ratio is large, the resonance characteristics become broad. Therefore, it seems that the OMI films with distributed island shape are useful for the wideband optical polarizing films for visible region. By using the OMI films with distributed island shape, we have designed wideband optical polarizing films for 400 - 500 nm by using aluminum and for 620 - 760 nm by using silver as metals. The extinction ratios of designed optical polarizing films are greater than 20 dB.

In the past it was observed that buck ball doped glasses showed enhanced optical nonlinearities. However, carbon nanotubes are much more stable than buck ball and should be a better choice for that purpose. Therefore we decided to investigate the possibility to produce carbon nanotubes doped tellurite glasses and measured their optical nonlinearities. Tellurite glasses already have a larger nonlinearity compared to silica, and other, glasses. We produced TeO₂-ZnO tellurite family glasses doped with multi wall Carbon Nanotube (CNT). The CNTs acquired from Carbolex were vigorously mechanically mixed with the tellurite glass precursors and melted in platinum crucible around 650°C in a controlled atmosphere inside an electrical induction furnace. We used the lowest temperature possible and controlled atmosphere to avoid the CNT oxidation. The glass melt was cast in a stainless steel and thermally treated at 300°C for 5 hours to relieve internal stresses. The samples were than cutted and polished to perform the optical characterization. We measured refractive index and thermo physical properties, such as vitreous transition T_g, crystallization onset T_x and melting T_f temperatures. Raman spectroscopy showed the possible presence of CNTs.

In this paper, we investigate simultaneous 853 nm + 1533 nm amplification, and wavelength conversion between 1533 nm and 853 nm in Er³⁺-doped fluoride fiber. Based on our simulation results, simultaneous 853 nm (⁴S_3/2→⁴I_13/2 transition) + 1533 nm (⁴I_13/2→⁴I_15/2 transition) amplification, and wavelength conversion between 1533 nm and 853 nm can be realized in Er³⁺-doped fluoride fibers with the excitation of a 974 nm laser diode, respectively. Furthermore, we investigate the interactions between 853 nm and 1533 nm amplifications, and discuss their effects on simultaneously 853 nm + 1533 nm amplifier. The crosstalk between 853 nm and 1533 nm signals is very weak because of relatively long lifetime (~10 ms) of the ⁴I_13/2 level. By introducing a cavity for 853 nm or 1533 nm lasing into the system, the possibility of wavelength conversion from 1533 nm to 853 nm or from 853 nm to 1533 nm in Er³⁺-doped fluoride fiber excited at 974 nm is clarified, which can be used as the wavelength converter or optical switch between public (the third window: ~1533 nm) and local (the first window: ~853 nm) networks in future networks.

Fiber Bragg gratings (FBGs) have been frequently employed for the strain and temperature measurement in many distributed sensor systems. For multipoint measurements with a very large number of measurement points such as smart structure applications, the multiplexing of FBG sensors is one of the most detrimental techniques to reduce both installation and operation cost for multipoint measurements. We proposed a new method of increasing the multiplexing capability of a multipoint FBG sensor system without increasing the system complexity by providing a unique spectral response to each FBG at a different location as an identification tag. FBG elements were fabricated to furnish reflectance spectrums to have a multi peaked structure. The number of sensors in the present spectral tag method increases as a multiple power of N, the number of spectral code. The free spectral range available for spanning the parameter to be measured is as wide as a substantial fraction of the whole spectral bandwidth of the system.

A method for fabricating Ag coated beam splitter is reported. This is showing specific patterned transmittance by immersing glass substrates in the mixture of H₂SO₄ and H₂O₂ to make negatively charged oxygen sites at silica surface and then in ethanolic solutions of AgNO₃ and butylamine. We controlled the soaking time and molar ratios of the mixture of AgNO₃ and butylamine to pattern % transmittance of electroless coated glass surface. Finally, we made a functionalized beam splitters showing step function like transmittance and applied this to make multiple laser beams for display and laser machining.

In_xGa_1-xAs bulk crystal is a lattice-matched substrate material for InGaAs-based laser diodes. We prepared an In_xGa_1-xAs with compositional fractions x ranging from 0 to 0.2 and the effect of Er impurity on the photoluminescence (PL) and Raman characterization of an Er-implanted In_xGa_1-xAs bulk crystal was studied. From the results of PL and Raman spectroscopy, it was found that the implantation damage in In_xGa_1-xAs:Er sample is recovered at a temperature of 700°C by the thermal annealing. Maximum PL intensity of Er-related emission was obtained for the In_xGa_1-xAs:Er sample annealed at 700°C in the compositional fractions ranging from 0 to 0.2.

In the last years, the performance of ytterbium doped high power silica fiber lasers has been remarkably improved. Increasing attention has been paid to the role of material composition, impurities and atomic defects, because the extreme power load and the complicated fiber structure make great demands on material properties and preparation technology. Recently, with the further growth of output power, the problem of photodarkening has been identified as a critical issue for fiber laser devices. Here we report on developments aimed at increasing efficiency and power stability of ytterbium doped laser fibers. The optical properties of preforms and fibers made by MCVD and codoped with high phosphorus contents were investigated for a wide range of the ytterbium concentration. Moreover, the influence of the collapsing atmosphere on the properties was studied. The observed spectral effects, photodarkening and laser efficiency were correlated with changes in fiber composition and process conditions. It could be shown that phosphorus codoping leads to remarkably different and advantageous fiber properties compared with the usual aluminium codoping.

We develop our previous considerations for one of the most important problems related to optimizing the performance data of a new acousto-optical spectrometer for the analysis of radio-astronomical signals. The main attention is paid to estimating the side lobes of light distributions inherent in an individual resolvable spot in the output Fourier plane, governing the dynamic range of that spectrometer. At first, we analyze the Akhieser mechanism responsible for linear attenuation of both longitudinal and shear elastic waves in isotropic solid states. Similar analysis can be directly applied to crystalline materials as well in all the cases of passing elastic wave along the acoustic axis in crystals. Then, we estimate the influence of the acoustic attenuation along a large-aperture acousto-optical cells operating in a one- and two-phonon light scattering regimes. In so doing, the optimal operating points are discussed for both these regimes. Finally, the combined effect of the acoustic attenuation and the incident light beam apodization is studied from the points of view of optimizing the levels of side lobes and minima in light distribution of an individual resolvable spot in focal plane of the integrating lens and, consequently, estimating potential limitations of the dynamic range.

Fabrication of channel waveguides in Er-doped tungsten-tellurite glasses was recently demonstrated. In order to get a deeper understanding of the process and to optimize the characteristics of the waveguides, we fabricated a set of planar waveguides, each of 7 mm × 7 mm lateral dimensions, in an Er-doped tellurite glass sample by implantation of 1.5 MeV nitrogen ions. Doses of the implanting ions ranged from 1 · 10¹⁶ to 8 · 10¹⁶ ions/cm². The samples were studied using interference phase contrast microscopy (Interphako), m-line spectroscopy and spectroscopic ellipsometry. The results show that a barrier layer of reduced refractive index was created around the range of the implanted ions at every dose. It is hoped that combination of the results obtained in these experiments with simulations for channel waveguides will make it possible to optimize ion-implanted fabrication of integrated optical components in this tellurite glass.

We developed a novel waveguide fabrication technology, i.e., femtosecond (fs) pulse laser assisted self-writing waveguide technology, to overcome problems of standard technologies, such as time consuming and high cost. Based on a light induced self-written (LISW) waveguide fabrication technology, a 488nm cw laser was launched through an optical fiber into UV curable resin. At the same time a 800nm fs laser was additionally used as a 3D position selective assistant beam. As the UV resin was cured by the 488nm laser and 800nm fs laser irradiation, a fiber/waveguide connecting 2D/3D waveguide was easily fabricated.

Optical sensors for the automotive industry need to be robust, high performing and low cost. This paper focuses on the impact of automotive requirements on optical sensor design and packaging. Main strategies to lower optical sensor entry barriers in the automotive market include: Perform sensor calibration and tuning by the sensor manufacturer, sensor test modes on chip to guarantee functional integrity at operation, and package technology is key. As a conclusion, optical sensor applications are growing in automotive. Optical sensor robustness matured to the level of safety critical applications like Electrical Power Assisted Steering (EPAS) and Drive-by-Wire by optical linear arrays based systems and Automated Cruise Control (ACC), Lane Change Assist and Driver Classification/Smart Airbag Deployment by camera imagers based systems.

There has been a strong interest in materials with nanometer dimensions because of its immense new applications in sensors, detectors, amplifiers, novel laser sources and emitters. Trivalent-erbium doped Y₂O₃ nanoparticles have been synthesized, and their spectroscopic studies have been carried out using visible laser excitation. The size estimation of the nanoparticles using atomic force microscope will be presented. The upconversion mechanism and laser power studies for the different emissions from Er³⁺ doped nanocrystals will also be presented.