This PDF file contains the front matter associated with SPIE Proceedings Volume 8069, including the Title Page, Copyright information, Table of Contents, Introduction, and the Conference Committee listing.

An integrated optical interleaver has been demonstrated in SOI platform using large cross section single mode rib waveguide structures. The 2×2 device structure is in fact an unbalanced Mach Zehnder Interferometer formed by cascading two identical directional couplers. The device was designed to separate alternate ITU channels operating at λ ~ 1550nm. The fabricated devices have been characterized in terms of insertion loss, polarization and wavelength dependencies, channel extinction etc. The first prototype device operating at ~ 100 GHz ITU channel spacing has been observed to be slightly polarization dependent and a channel extinction of ~ 8 dB was recorded for TE polarization.

We demonstrate widely tunable high power distributed feedback quantum cascade laser array chips that span 190 nm and 200 nm from 4.4 um to 4.59 um and 4.5 um to 4.7 um respectively. The lasers emit single mode with a very narrow linewidth and side mode suppression ratio of 25 dB. Under pulsed operation power outputs up to 1.85 W was obtained from arrays with 3 mm cavity length and up to 0.95 W from arrays with 2 mm cavity length at room temperature. Continuous wave operation was also observed from both chips with 2 mm and 3 mm long cavity arrays up to 150 mW. The cleaved size of the array chip with 3 mm long cavities was around 4 mm x 5 mm and does not require sensitive external optical components to achieve wide tunability. With their small size and high portability, monolithically integrated DFB QCL Arrays are prominent candidates of widely tunable, compact, efficient and high power sources of mid-infrared radiation for gas sensing.

We report a comprehensive study of the effects of polarized optical injection in long-wavelength Vertical-Cavity Surface Emitting Lasers (LW-VCSELs) emitting at the telecom wavelength of 1550nm. We analyze the properties of the polarization switching and bistability that can be induced in a 1550nm-VCSEL under orthogonal and arbitrary polarized optical injection. Additionally, we study the injection locking bandwidth of these devices when subject to different polarized optical injection. Furthermore, we also analyze the relationship existing between the injection locking bandwidth and the polarization switching range when the device is subject to orthogonally-polarized optical injection. Finally, we have identified regions of different nonlinear dynamics outside the injection locking bandwidth, including regions of periodic dynamics (such as limit cycle and period doubling) and chaos when these devices are subject to parallel and to orthogonal optical injection. This rich variety of nonlinear effects observed at 1550nm offers exciting prospects for novel practical uses of VCSELs in optical switching/routing applications in optical networks.

This paper reports the development of an infra-red circa 193THz (~1.5μm) frequency tunable laser source selected and evaluated for photonic environment sensing systems. LIDAR (LIght Detection And Ranging) offers a method of remote wind speed measurement. Widespread deployment of the technique has been limited by the expense and complexity of LIDAR systems. However development of systems based on optical fiber and photonic components from the telecommunications industry promises improvements in cost, compactness, and reliability, so that it becomes viable to consider deployment of such systems on large wind turbines for the advance detection of fluctuations of wind speed. A monolithic multi-section laser, originally designed as a tunable source for telecommunications applications, has been modified and re-evaluated as a source for sensing applications, based on the technique of coherent laser radar (CLR), and coherent doppler LIDAR (CDL). A tunable frequency optical source should fulfil specific technical criteria to fulfil the applications requirements; speed of frequency selection, absolute accuracy of emitted frequency, spectral purity, and stability. Custom electronics and firmware were developed to realise an improvement in frequency switching speed by a factor of 10 relative to equivalent commercially available telecoms (DBR) sources, satisfying the target application requirements. An overview of the sensing architecture is presented, a detailed description of the fast tuning process described, including the custom hardware and firmware, and specifically the laser energising sequence. The results of the laser module are then presented with detailed consideration of the target application.

Optically triggered surface channel MESFETs were fabricated on commercial polycrystalline diamond to be tested as fast UV activated switches. Devices with an opaque-gate and asymmetric structure were designed in order to improve charges photogeneration within gate-drain region. The sensitivity to UV light was demonstrated by using both modulated over gap radiation and laser pulses at 193 nm, well over the diamond band gap. Linearity with the power light was demonstrated as well as the parabolic dependence of the photogenerated current on the gate-source voltage when the transistor is in saturation. The transient response to 193 nm laser pulses in the nanosecond regime shows as the photogeneration process and charges collection to the drain contact are completed in a time scale of few nanoseconds.

We investigate the design of binary grating structures, e.g. resonance waveguide filters (RWFs), with subwavelength feature sizes, taking the temperature dependence of different material parameters into account. Our final goal is to demonstrate devices with athermal operation. We design the binary grating structures to be made in polymer substrates, such as polycarbonate (PC), due to their potential for low cost, mass fabrication. The high thermal expansion coefficient (TEC) of polymers, compared to inorganic optical materials, enhances the thermal sensitivity of the grating structures. The gratings are designed using Fourier Model Method (FMM) by considering both thermal expansion and thermo-optic effects on the resonance wavelength shift. The fabrication of RWF structures is proposed by e-beam lithography, creating a master stamp and copying the structures into a polymer substrate by some replication techniques, followed by an ALD deposition of TiO₂. When the resonance waveguide grating RWG is designed for nearly room temperature operation at a peak wavelength of 633 nm with a full width half maximum FWHM of 3 nm (TM mode reflectance), the peak wavelength shifts 0.2 nm /5⁰C when only the TEC is taken into account. However, taking into account also the thermo-optic coefficients TOCs of PC and TiO₂, the peak position shifts to 0.4 nm/ 5⁰C on the opposite side of spectral central wavelength. Thus the overall shift reduces to 0.2 nm /5 ⁰C, illustrating partial athermalization. It was also observed that thermo-optic coefficient TOC contributed more significantly than TEC effect. The wavelengths shift was almost linear with respect to temperature for both effects and showed slopes of 0.0673, 0.0422 and 0.02352 for TOC, TEC and combined effects, respectively.

Utilization of the photorefractive effect for creation of the waveguiding region may offer rather cheap, easy, "green" (chemicals-free) and flexible way to fabricate the waveguiding-based devices for integrated optics in proper media. We present results of a single waveguide fabrication in LiNbO₃:Fe crystal by means of a single Ar⁺ ion laser beam with special spatial distribution of intensity. The process of the waveguide creation is, in real time, monitored by means of Mach-Zehnder interferometer. According to interpretation of the resulting interferogram this allows to control the time of the exposure needed for reaching the desired difference between the refractive indices of the waveguiding and surrounding regions. The waveguiding properties of the structure are practically demonstrated.

Detectors sensitive to ionizing radiations were assembled from high-purity single-crystal diamond plates with Ti/Au injecting contacts. Spectrally resolved photoconductivity measurements in the range 2-6 eV were used to infer the defect density in the diamond bulk material using silver contacts. The electrical behavior of annealed Ti/Au contacts was analyzed in the dark through current-voltage measurements in the range ±500V (10⁴ V/cm). Although contacts appear to be ohmic in the dark, two different transport regimes were found under x-ray irradiation as a function of the applied bias voltage. Recombinative regime at low bias and space charge limited injection regime at high bias were evidenced. The analysis of the photocurrent's module and phase under x-ray modulated irradiation allowed us to highlight photoconductive gain phenomena mitigated by a Poole-Frenkel field-assisted detrapping process. Through the analysis of device's impedance under irradiation, a lumped-elements electrical circuit is proposed to explain the detector's dynamic behavior.

We investigate collections of Nitrogen-Vacancy (N-V) Centers in diamond crystals coupled to a circuit QED system of a coplanar waveguide (CPWG) resonator. Our analysis reveals that different symmetry axes oriented N-V centers in the diamond host can be grouped into bosonic modes of collective quasi-spin wave excitations so that the hybrid system can be described as an analog of an exciton-polariton type cavity QED model. We examine such model for quantum state transfer among distinct crystallographic groups of N-V centers in a single diamond as well as two spatially distant diamonds. Rabi oscillations, mode entanglement, possible use of N-V classes as spin ensemble qubits and an implementation of continuous-time quantum random walk are discussed.

In a quasi- zero-average-refractive-index (QZAI) metamaterial, the light scattered out is extremely directive (Δθout = 0.06°), in despite of a divergent source at near infrared wavelength (λ=1.55 mm). In this paper we discuss and experimentally demonstrate that this is possible when the light is coupled with diffraction order of a grating with alternating complementary media. The experimental data prove with a high degree of accuracy also the strong vertical confinement of the beam even in the air region of the metamaterial, where any simple vertical confinement mechanism is absent. This extremely sensitive device works on a large contact area and open news perspective to integrated spectroscopy.

We report on the fabrication and characterization of opal-based photonic crystal heterostructures. These heterostructures are created by using multilayer deposition of silica and polystyrene spheres. In the specific the fabricated structures involved both different lattice constant and dielectric function. Scanning electron microscopy (SEM) and NIR-VIS transmittance and reflectance spectroscopy are used to characterize the systems. The SEM images show good ordering of the two-layer colloidal crystals constituting the heterostructures. The transmittance and reflectance spectra measured from the (111) plane of the heterostructure show that the composite colloidal photonic crystals have double photonic stop bands that matches the stop bands of the individual photonic crystals. This behaviour can be seen as a superposition of the properties of each individual layer.

We describe the development of optical waveguides and adiabatic tapers based on SiON-glasses for a lab-on-chip device with fluorescence optical detection. Sensing is based on evanescent near-field excitation of biomolecules captured on the surface of a thin waveguide. First, the composition of SiON waveguides was optimized to reduce losses for visible light. Waveguides with refractive index of ~1.63 showed propagation losses of ~0.8-0.9 dB/cm at 633 nm. A low loss adiabatic taper was developed to convert efficiently the light from a multi mode waveguide into a thin mono-modal one. Design of the taper was done by calculating numerically the transmission efficiency using a finite-difference time-domain method (FDTD). Simulation results show that losses lower than ~1 dB are obtained for taper lengths of 100 to 300 micron, which indicates an efficient mode conversion. Based on this, tapers of different lengths were realized by grayscale lithography and by reactive ion etching. Their optical testing shows best insertion losses of ~1 dB at 633 nm for multimode to monomode waveguide transitions.

We demonstrate electro-optical tuning and modulation of the optical resonances of a silicon microsphere placed on an optical fiber half coupler and immersed in a nematic liquid crystal. The relative refractive index between the microsphere and the liquid crystal is controlled by an applied external AC electric field. The tuning and modulation of the microsphere optical resonances is monitored with the transmission and elastic scattering signals.

The solar cells efficiency may be improved by better exploitation of the solar spectrum, making use of the downconversion mechanism, where one high energy photon is cut into two low energy photons. The choice of the matrix is a crucial point to obtain an efficient down-conversion process with rare-earth ions. When energy transfer between rare earth ions is used to activate this process, high emission and absorption cross sections as well as low cutoff phonon energy are mandatory. A low phonon energy host lattice reduces non-radiative transition rates leading to the increase of the luminescent quantum yield and of the energy transfer efficiency. Recently, some studies have demonstrated that fluoride and oxyfluoride glasses may be valid systems to support an effective quantum cutting process. As a fluoride material, the relatively low phonon energy, around 600cm^-1, of the ZLAG (70ZrF₄ 23.5LaF₃ 0.5AlF₃ 6GaF₃ in mol%) glass makes it highly suitable for applications involving energy transfers. In this study, attention is focused on the assessment of the energy transfer efficiency between the Pr³⁺ and Yb³⁺ ions in bulk fluoride glasses ZLAG.

Thin silicon rich oxide (SiO_x) films were deposited using the LPCVD (Low Pressure Chemical Vapour Deposition) method. Silane diluted in argon and oxygen were used as the reactant gasses, and the deposition temperature was kept constant at 570 °C. The films were deposited on silicon (111) and on fused silica substrates. Films with the different values of the oxygen content were deposited by varying the ratio of the flows of oxygen and silane in the horizontal tube reactor. The films were characterized in terms on the surface quality (by X-ray specular reflectivity and scanning electron microscopy) and in terms of the oxygen content x (by time of flight elastic recoil detection analysis). The films were found to have a very smooth, homogeneous surface and the oxygen content was found to vary from x=0 to x=2 in dependence on the deposition parameters. The refractive indices of the films were measured both in the visible (405 nm) and in the infrared (1319 nm and 1542 nm), compared to the values which the Bruggeman's effective medium theory predicts for such thin films, and were found to be in good agreement. The position of the Si-O stretching peak in the infrared absorption spectra was used to draw some conclusion about the distribution of the silicon and oxygen atoms inside the amorphous SiO_x matrix. The atoms were found to be inhomogeneously distributed inside the amorphous matrix, with the average number of oxygen atoms in the vicinity of a given silicon atoms being lower than x.

Silicon oxynitride (SiON) films have been found to possess extremely useful properties for optical applications. In optoelectronics, a major advantage of this material is the ability to tune the refractive index from 1.45 to 2.00, allowing designers the flexibility to custom tailor and optimize the refractive index value in the targeted optical device. In addition, its minimum allowable bending radius is much lower compared to other silica materials. This opens up the possibility of miniaturizing integrated photonic systems. Moreover, silicon oxynitride prepared using Plasma Enhanced Chemical Vapor Deposition (PECVD) can be deposited at high growth rates while exhibiting good homogeneity with wide refractive index tuning range making it a well-suited core layer for planar waveguide technologies and microphotonic devices. In this research work, the deposition process and the properties of SiON are discussed. The obtained refractive index as well as the X-ray photoelectron spectroscopy (XPS) analysis are highlighted. Furthermore, FTIR results as a function of the process parameters are presented and their influence on the film properties is discussed.

Polymers are important materials in fabrication of photonics devices due to their good optical properties, such as, high transmittivity, versatile processability also at low temperatures allowing potential for low-cost fabrication. A critical requirement in the fabrication of integrated optical devices has been selecting a most suitable method for patterning the ridge bounding the optical mode in the waveguide. In this paper, we discuss a UV-imprint fabrication of polymeric single-mode waveguides with different configurations: ridge type, inverted rib type and layered composite waveguides. A ridge waveguide type consists of a strip waveguide superimposed onto a slab waveguide made of the same material. When patterning a ridge by imprinting technique, a residual layer is formed underneath the imprinted ridges. A too thick residual layer might cause a loss of propagation mode due to power leakage to the slab guide, which might require a subsequent etching step. In inverted rib waveguide structure, a groove of cladding material is patterned by imprinting. This is followed by the filling of the groove with a core material. From the imprint fabrication point of view, the fabrication tolerances can be relaxed because the residual slab layer underneath the waveguide can have arbitrary thickness. Besides fabrication of above mentioned waveguide structures, we also investigate the possibility to produce composite waveguide devices by depositing inorganic thin films with high-refractive index on UV-imprinted polymeric structures with low-refractive. The purpose to use composite structures is to manipulate the optical field distribution in waveguides.

Miniaturization of photonic devices is required by various applications such as data storage and processing, optical communications, and metrology. This request can be met by new optical designs, miniaturized components, and advanced packaging technologies. Design, assembly, and characterization of a miniaturized photonic wavelength-division multiplexing (WDM) device for optical measurements are presented. The device features the use of gradient index lenses (GRIN-lens) and the utilization of an adhesive free, laser-based joining technology. Solderjet Bumping offers flux-free soldering in a localized inert nitrogen atmosphere with minimized input of thermal energy, thus allowing for the joining of fragile materials such as glass or brittle ceramics. The proposed system design consists of a system platform made of borofloat BF33 with a footprint of approx. 30x20 mm². Mechanical stops also made of borofloat glass, fiber-ferrules with a length of approx. 5 mm, and GRIN-lenses with a length of 4.05 mm are attached to the base-plate by solder joints. The solder process uses tin-silver-copper (Sn3Ag0.5Cu) solder spheres with a diameter of 200, 400, and 760 μm. A fiber-to-fiber coupling efficiency of 72 % is demonstrated using uncoated components.

A diffusion process controlled modelling of Titanium-indiffused Lithium Niobate (Ti: LiNbO₃) channel waveguides (of μm dimension) for Machzehnder Interferometer (MZI) switch has been presented. The effect of various indiffusion process parameters e.g. dopant strip thickness, lateral and vertical diffusion length on the insertion loss has been taken care of, to reduce the switch losses. Transition losses in the curved waveguides of the structure are also minimized by selecting low loss bend structures to increase overall performance of the switch. The computed results for switch performance are in good agreement with the published data.

Dual-broadband pure rotational CARS (RCARS) is nowadays a well-developed gas phase measurement technique. Nevertheless there are challenges for technical applications due to stray light interference, soot emission or droplets. Beside this for diffusion flames also a strong, unknown and varying non-resonant background signal is contributing to the CARS signal. Possible applications of time-resolved pure rotational coherent anti-Stokes Raman spectroscopy for different applications are demonstrated and its potential of for gas-phase thermometry is investigated. The field of application covers studies on flame research especially sooting flames as well as its use in technical combustion systems e.g., for the determination of the gas-phase temperature in the vaporizing spray of a GDI injector. A new advantageous approach by using picosecond (ps) laser sources as a diagnostic tool is also demonstrated. By time-delaying the ps probe laser beam problems due to stray light interference, soot emission or droplets can be reduced tremendously of even eliminated.

The paper presents a CMOS sensor array for the detection of speckle movements, for applications requiring accurate movement tracking of arbitrary surfaces. The array is made of eight sensors incorporating each a spatial comb filter with a pitch of 2.8μm so as to be direction-sensitive to the movement of speckles with corresponding direction and spatial frequency, defined by the optical geometry of the system. The circuit is used with an array of micro-lenses placed between the sensor and the laser-illuminated surface. With speckle statistics (contrast, size) being independent on the surface properties, the detection works on virtually any surface. The system is operated at a sampling frequency of 64kHz. Integrated into a 180nm CMOS process, the circuit active area occupies 1.9mm² and consumes 290μW at full speed, allowing a maximal stable tracking speed of the surface of 0.25 m/s and a tracking accuracy of about 5μm.

We propose a simple and innovative diffractive method for circular dichroism (CD) spectroscopy. It enables real-time measurements and suppress the artifacts introduced by anisotropic specimens and nonideal optical elements in conventional CD spectrometers. The method is based on a single cycloidal optical axis grating and takes advantage of its peculiar optical diffraction behavior. We prove that the true CD spectrum of a general anisotropic medium could be measured in the spectral range of interest, exploiting unpolarized white light and the intrinsic spectral selectivity of the grating. Two experimental approaches have been pursued to create the cycloidal optical axis grating, both based on polarization holography and liquid crystal photoaligning technology. The gratings are replicas of the polarization holograms in thin-films of azodyes, either in low molar mass liquid crystal cells or in reactive mesogen layers.

We investigated the properties of a triangular microresonator using the total internal reflection (TIR) mirrors with a long evanescent field around the critical angle. For the sensitivity analysis, we have calculated the mirror offset due to the Goos-Hänchen effect and the resonance shift of the triangular resonator with the refractive index change of the outer region in the TIR mirror. The mirror offset is increased up to 0.8 μm for the transverse electric (TE) polarization and 2.0 μm for the transverse magnetic (TM) polarization to the incident angle of 18°. Then, the resonance shift of 417 pm for the TM polarized light and 34 pm for the TE polarized light were observed, respectively, by changing the refractive index of 4×10^-5. The measured extinction ratio of triangular ring resonator was about 6 dB near 1550 nm, in where the incidence angle of the TIR mirror inside the resonator was 18°.

Optical resonances are observed in the elastic light scattering form high refractive index glass microspheres placed on a single mode optical fiber coupler and in a liquid crystal. Placing the liquid crystal on the optical fiber coupler increases the non-resonant scattering, whereas placing the liquid crystal away from the optical coupler increases the resonant scattering. Optical resonances blue and red shift due to the placement and removal of the liquid crystal.

For the use in cost-effective optical interconnection of opt-electronic printed wiring boards (OE-PWBs), we have developed novel optical interconnect devices and coupling methods simplifying board to board optical interconnect. All these are based on the self-written waveguide (SWW) technology by the mask-transfer method with light-curable resin. This method enables fabrication of arrayed M × N optical channels at one shot of UV light. Very precise patterns, as an example, optical rod with diameters of 50μm to 500μm, can be easily fabricated. The length of the fabricated patterns ,, typically up to about 1000μm , can be controlled by a spacer placed between the photomask and the substrate. Using these technologies, several new optical interfaces have been demonstrated. These are a chip VCSEL with an optical output rod and new coupling methods of "plug-in" alignment and "optical socket" based on SWW.