This PDF file contains the front matter associated with SPIE Proceedings Volume 7138, including the Title Page, Copyright information, Table of Contents, the Conference Committees listing, Introduction, Welcome Address, Conference Photos, SPIE Best Student Presentation Award, CSSF Young Scientist Prize, and a Sponsors page.

In his 1917 "On Quantum Theory of Radiation" paper Albert Einstein introduced the concept of amplification of radiation through stimulated emission with coherence. This concept had not been applied in practice until 1952 when Joseph Weber, followed by Townes, Basov and Prokhorov, developed the theory and started working on the construction of masers. The first maser was demonstrated by Townes' team in 1953. Many researchers began thinking about making an "optical maser", but the transition from centimeter to nanometer waves posed a problem. Well funded researchers in the USA and Soviet Union put their efforts into making an "optical maser". In May 16, 1960 an unknown and underfunded researcher, Theodore Harold Maiman, won the race and demonstrated a fully functional ruby laser. The scientific world was astonished by its simplicity and elegance. Maiman's short paper describing the invention appeared immediately in Nature magazine. This invention caused an avalanche of new laser developments followed by the growing number of applications in almost all fields of our lives. Ted Maiman died in 2007 in Vancouver, just 13 days before the 47th anniversary of the invention of the laser. The intention of this paper is to focus on the life of the scientific maverick and great man.

High Power Lasers have been used for years in corresponding applications. Constantly new areas of application and new processes have been demonstrated, developed and transferred to fruitful use in industry and society. In the last years diode pumped solid state lasers in the multi-kW-power regime at beam qualities not far away from the diffraction limit have been developed. Consequently, a new area of applicability has opened. Many advancements can be realized even in classical applications like cutting (remote, 1µm-radiation), welding (high speed, remote), and surface treatment, however also new processes are established increasingly on that basis. Among others, the most important are 3-d metal build up in metal, ceramics and biocompatible polymers, selective laser melting, micro and nano-processing (ablation, structuring, polishing) and bio-photonic applications in diagnosis, microscopy and medical therapy. Remote contactless materials analysis by Laser induced breakdown spectroscopy LIBS allows new concepts and system in the recycling of metals and other raw materials.

We discuss wavelength stabilized all-epitaxial Tilted Cavity Lasers (TCLs). Optical cavity of a TCL favors propagation of only one tilted optical mode ensuring wavelength-selective operation. The possibility of full control of the thermal shift of the lasing wavelength d λ/dT in TCL including positive, zero or negative shift, is proved theoretically. Broad-area (100 μm) 970-nm-range devices have been fabricated showing a high temperature stability of the lasing wavelength (0.13 nm/K), a high power operation (> 7 W in pulsed mode and > 1.5 W in continuous wave (cw) mode), and a narrow vertical far-field beam divergence (FWHM ~ 20°). Single transverse mode edge-emitting 4 μm-wide-ridge TCLs demonstrated high-power spatial and spectral single mode cw operation with a longitudinal side mode suppression ratio (SMSR) up to 41.3 dB at 93 mW output power. Such a result is similar to the best values achieved for DFB lasers in the same spectral range, while no etching and overgrowth is used in present case.

In conventional Adaptive optics (AO) system, wavefront aberration is measured by wavefront sensor. However, a point source is usually not available in most imaging systems. Therefore development of deformable mirror control scheme in adaptive optics system based on vision information will extend the application area of AO technique. A focus measure (FM) is a measure of image quality and can be calculated from image data obtained from the image sensor. It can be used to find the optimal shape of the deformable mirror that compensates the wavefront aberration. In this paper, we analyze the performance of focus measures under different types of wavefront aberrations. The relation of FM vs. the aberration strength is analyzed systematically for different aberration modes and different FM functions. The FM performance under combination of aberrations is also investigated. This research supplies a guide for selection of the suitable FM function and strategy for control of deformable mirror in the AO system.

This paper presents new experimental results on the sensitivity of a microstructure fiber (MSF) to toluene and ethanol in gaseous mixtures with nitrogen. This sensitivity is compared with that determined with a single-capillary fiber (CF). The results obtained both with the fibers modified by a porous detection layer prepared by the sol-gel method from tetraethoxysilane are presented. MSF with air holes arranged in one shell and coated with an UV acrylate jacket was prepared by using the "stack and draw" technique. CF coated with polydimethylsiloxane optical cladding was prepared. The segments of the prepared fibers were modified by a porous polysiloxane layer applied onto the hole walls. The sensitivity of the MSF and SCF to gaseous toluene and ethanol in nitrogen was determined from spectral changes of C-H and O-H absorption bands in a range of 1300-1800 nm. Limits of detection of 0.008 and 0.02 vol.% have been determined for toluene and ethanol, respectively.

In this letter, we report on the study of a new all-fiber laser source suitable for coherent Doppler LIDAR use in the eyesafe domain. The laser consists on a MOPA configuration where the Master Oscillator is a modulated ultranarrow (< 8 kHz) fiber laser. The optical amplifiers are also all-fibered and make use of a new Large Mode Area (LMA) index pedestal fiber that is very effective in limiting the non-linear effects without quality degradation of the laser beam. The amplified pulses have a maximum energy of 0.15 mJ for a duration of 340 ns at a repetition rate of 15 kHz. The average output power of the laser is 2.5 W, free of Stimulated Brillouin Scattering and with a measured M² = 1.3.

Gauge block calibration for dimensional metrology standards are made by means of laser interferometry procedures and uncertainty is typically calculated using the recommendations of the Guide to the Expression of Uncertainty in Measurement (GUM). This method does not appear very useful for complicated and non-linear model equations as occurs in gauge block interferometry. Under this context, a Monte Carlo method is applied to evaluate the uncertainty of the model function. Input distributions are generated taking into account the value of the physical magnitudes, type of probability distribution and standard uncertainty value. These values are particularized for the room conditions and instruments used in the Metrology Laboratory of Galicia (LOMG), Spain. Obtained results show that the output data fit correctly to a normal distribution (Central Limit Theorems hypothesis can be assumed) and show the potentiality of applying Monte Carlo methods to the uncertainty evaluation in gauge block interferometry.

Surface optical and magneto-optical properties of as-quenched (AQ) Co₆₆Fe₄Si₁₅B₁₅ amorphous ribbons are studied using the magneto-optic vector magnetometry. Both in-plane magnetization components (longitudinal M_L and transversal M_T) detect typical uniaxial magnetic anisotropy with the easy axis close to the ribbon axis. Moreover, the total magnetization vector |M|/M_S = (M_L²)+ M_r²)^0.5/M_S indicates that coherent rotation of magnetization dominates. In the regions, where |M|/MS < 1, we observe the magnetic domains using the Kerr optical microscope. The fact that domain structure closely relates with the magnetic anisotropy is confirmed. Surface optical (refractive index) and magneto-optical (the Voight constant) properties of AQ ribbon are obtained by comparing the measured magneto-optical Kerr angles at different incident angles with the theoretical model based on the light propagation in layered anisotropic media.

In chemical, oil, and food industries, there are still higher requirements on miniaturization of optical sensors for a concentration measurement of gases e.g. a CO₂, O₂, and NH₃. The paper deals with development of miniaturised optical sensor for an aqueous carbon dioxide measurement using a sensitive polymer layer. The optical sensor module consists of two parts, a remission sensor and a removable layered structure (with incorporated dyed polymer) which is closely placed on the surface of a remission sensor. A dyed polymer film is used as an optical-chemical transducer working on a principle of colour changes caused by a chemical reaction of an analyte and indicator dye. A novel remission sensor module was developed for an evaluation of the spectral absorption changes of sensitive polymer layer. The remission sensor module composed of LED diodes located in a central cavity of the sensor module and PIN diodes situated around the cavity. The LEDs emit light with optimised wavelengths and irradiate the polymer film. Light response (the changes of the spectral absorption) of the irradiated polymer film is detected by PIN diodes. A colour shift is further analyzed and evaluated by electronics without using a photometer.

Successful room-temperature generation of the Pr:YAP laser radiation at a wavelength of 747 nm was demonstrated. Flash-lamp pumped Pr:YAP laser was operated in free-running pulsed regime at room temperature. Permanent laser action was reached by means of special UV color glass plate filter placed directly into the laser cavity. The maximum output energy and the pulse length reached were 102 mJ and 92 μs, respectively, at 121 J pumping (pumping flash-lamp pulse length was 110 μs). Stimulation emission excitation threshold was observed at 20 J.

We are reporting our results in research and development in the field of avalanche semiconductor single photon detectors and their optimization for the selected space projects. Our goal was a development of a solid state photon counting detector capable of high precision photon arrival time tagging. For the application in laser time transfer via satellite the detector should be able to operate in both gated and non-gated modes; additionally the extremely high background photon flux should not disable the detector operation. We have developed the novel active quenching and gating electronics circuit, which enables both the gated and non-gated operation of the K14 Single Photon Avalanche Diode (SPAD). The performance of the optimized photon counting detector has been verified in a series of indoor calibration tests. The detection probability, timing resolution and detection delay stability have been measured in both operation modes under various background photon flux conditions. The detector design and construction is a promising candidate for the space project of Laser Time Transfer prepared by China. The experimental results are presented.

The interconnection complexity of the PCB (Printed Circuit Boards) is still growing and new technologies are introduced in the production of high density printed circuit boards. Recently the Laser Direct Imaging (LDI) technology is used for imaging electric circuits directly on PCB without the use of a phototool or mask. We presents our laboratory system for Laser Direct Imaging designed for tracks and spaces on PCB with minimum track/space widths distance of 50/50 μm. In comparison with conventional photolithography method, this technology is much better for 50/50 μm track and spaces. In our research we used photoresist with 50 μm resolution, but in case of using laser photoresists with better resolution (e.g. 25 μm) it is possible to image tracks in super-fine-line technology (25/25 μm). Our laboratory system for LDI consist of diode UV laser (λ=375 nm, P=9 mW), optical scanner head, telescope and XY planar table, which extends scanner head working area into 15 × 25 cm usable area. A sophisticated computer software was developed to control this system.

We describe in this paper an experimental arrangement for optical pumping of rubidium based on a high-power laser diode array. The emission spectrum of the array was narrowed by external injection locking technique by means of cw Ti:Sa resp. an extended cavity laser (ECL) based on a high-power laser diode. The array emission spectrum was reduced with the aim to achieve maximum efficiency of the Rb optical pumping process. By way of the external injection locking technique, the power spectral density at the desired wavelength 794.76 nm was increased about 9 times. The laser system was designed to be a crucial part of the HpXe (hyperpolarized xenon) production process.

In this paper we demonstrate simple wavelength tuning mechanism of pulsed diode pumped Nd:GdVO₄ laser in the grazing incidence geometry. The active material which is thin slab with wedged ends, acts as dispersive element and enables to tune wavelength of the generated radiation either to the commonly used 1063 nm line with π polarization, the 1066 nm line with σ polarization or simultaneous dual wavelength operation, just by tilting the resonator mirror. The detailed characteristics of the laser are presented.

Thin films of hydroxyapatite, hydroxyapatite doped with silver and thin diamond like carbon layers were prepared using KrF excimer laser deposition. Tooth prostheses, textile blood vessels and artificial heart valves were covered and tested. Examples of physical tests, and in vitro and in vivo analysis using minipigs and sheep are presented.

Medical endoscopy constitutes a basic device for the development of minimally invasive procedures for a wide range of medical applications, involving diagnosis, treatment and surgery, as well as biopsy sampling. Its minimally invasive nature results in no surgery, or only small incisions, which involves a minimal hospitalization time. The medical relevance of endoscopes relies on the fact that they are one of the most effective means of early stages of cancer diagnosis, with the subsequent improvement in the patient's quality of life. Flexible endoscopy by means of coherent optical fiber bundles shows both flexibility and a high active area. However, the parallel arrangement of the fibers within the bundle produces interference phenomena between them, which results in optical crosstalk. As a consequence, there is a power exchange between contiguous fibers, producing a worsening in the contrast of the image. In this work, this quality limiting factor is deeply studied. We quantitatively analyze crosstalk, performing several studies that show the limitations imposed to the endoscopic system. Finally, we propose some solutions by an analytical method to accurately determine the appropriate optical fibers for each particular design. The method is also applied to endoscopic OCT.

Polarimetry is widely known to involve a series of powerful optical techniques that characterize the polarization behaviour of a sample. In this work, we propose a method for applying polarimetric procedures to the characterization of biological tissues, in order to differentiate between healthy and pathologic tissues on a polarimetric basis. Usually, medical morphology diseases are diagnosed based on histological alterations of the tissue. The fact that these alterations will be reflected in polarization information highlights the suitability of polarimetric procedures for diagnostic purposes. The analysis is mainly focused on the depolarization properties of the media, as long as the internal structure strongly affects the polarization state of the light that interacts with the sample. Therefore, a method is developed in order to determine the correlation between pathological ultraestructural characteristics and the subsequent variations in the polarimetric parameters of the backscattered light. This study is applied to three samples of porcine skin corresponding to a healthy region, a mole, and a cancerous region. The results show that the method proposed is indeed an adequate technique in order to achieve an early, accurate and effective cancer detection.

Optical treatment of pathological tissues comprises techniques like Low Intensity Laser Treatment (LILT) or Photodynamic Therapy (PDT). PDT consists on the inoculation of a photosensitizer in the tissue, which tends to be accumulated in cancerous cells, and on the posterior optical radiation of the area. The photosensitizer, that can be topical or systemic, is excited and cell necrosis is provoked. The collateral harmful effects of other destructive techniques, like radiotherapy or chemotherapy, are avoided with PDT. PDT can also be used as a complementary technique of conventional excisional surgical operations. The application of PDT to skin disorders is straightforward due to the fact that it is an external and accessible tissue. In this work, we analyze the application of PDT to several skin pathologies and the results obtained, by means of mainly the usage of Metvix^R as a topical photosensitizer and with an optical source in the range of 635 nm. The analysis includes a predictive model of the PDT process, based on an optical propagation equation and a photosensitizer degradation approach that provides an estimation of tissue destruction.

Photodynamic diagnosis (PDD) is promising method of visualisation of premalignant and malignant lesions. PDD is consisted of two main agents: special chemical compound which is called photosensitizer and light. Photosensitizer has affinity to fast proliferating cells such as pre- or malignant. During light irradiation (with proper wavelength - corresponding to absorption peak of photosensitizer) photosensitizer gains energy and passes into excited singlet state S₁. Returning to basic singlet state S_n, leads to fluorescence. Due to difference between concentration of photosensitizer in lesion and normal tissue it is possible to obtain high contrast image of lesion. Case #1: 53 years old woman with basal cell carcinoma (BCC) in nasal region; 20% delta-aminolevulinic acid as a precursor of photosensitizer on eucerin base was used. Case #2: 57 years old woman with multifocal oral leukoplakia on cheek mucosa and tongue; 2% chlorophyll gel as photosesitizer was used. All photographs were taken in white light without any filter and in blue and UV light with orange filter: in both cases the total area of the lesions appeared to be larger than it has been clinically observed. Thus, the PDD might be helpful in evaluation of margins of surgical excision of such lesions.

Laser-assisted lithotripsy is a minimally-invasive method for destroying or disruption of human urinary stones. For this purpose laser light delivered through the flexible sealed waveguide or fibre could be utilized. On the output end of the delivery system the laser ligth is focused onto the surface of urinary stones with various size and various composition. In clinical urological practise the Ho:YAG laser with the generated wavelength 2100 nm operated in free-running regime is commonly used. The aim of our investigation was to compare the damage effects of Ho:YAG laser radiation with the promissing Er:YAG laser radiation. The Er:YAG laser generates radiation with the wavelength 2940 nm, which coincides with the local absorption maximum of water. We have compared the laser effect with the help of uniformly produced model samples made from special plaster. The size of the samples was 10×10×10 mm. The perforation and disruption effectiveness of Ho:YAG and Er:YAG laser radiations were performed and compared. In the final step the laser lithotripsy of human urinary stones was tested with Er:YAG laser radiation delivered through the special COP/Ag hollow waveguides sealed with fused silica cap.

Progress in gene- and biotechnology has opened a new application domain of optics - i.e. biophotonics. In this field, optical methods are developed and applied to the functional analysis of tissues and cells as well as to cell manipulation. Growth processes, e.g. in the developing stage of tumours, reveal themselves through changes in their elasticity properties and by micro movements. Holographic-interferometric methods have proven their capability to analyse local elasticity distribution and micro movements. In combination with microscopic optics, these "microinterferometric" methods provide a new basic technology - i.e. Digital Holographic Phase Contrast Microscope - for the analysis, manipulation and utilisation of living systems down to the nanoscale. Modular digital holographic microscopy allows maker-free, quantitative, contactless, fast, full field, high resolving (< 5 nm axially) imaging and analysis of living cells and can be combined simultaneously with most of the modern microscopic technologies. In this way, diagnostics standards for cell differentiation and manipulation as well as for cellular tissue engineering and other life sciences domains can be extended.

Planar-integrated optical biosensors based on the interferometric evanescent wave sensing principle facilitate highly sensitive label-free detection of biomolecules. In this work, we present a novel polymer waveguide device concept that allows for cost effective fabrication of disposable sensor chips by utilizing injection moulding and spin-coating. Surface grating couplers are used in combination with lateral tapers to couple light in and out of the biosensor. The coupling strength of these polymer gratings is increased by applying a thin inorganic high-index coating, which allows reducing the grating size and thus achieving efficient lateral tapering into single mode waveguides. The sensor concept, design of the waveguide components as well as first experimental results of the injection moulding process, the grating couplers and the Mach-Zehnder interferometers are presented.

In this work, we focus on Multi Quantum Well (MQW) as a semiconductor structure which is orthogonal to the direction of the propagation of the radiation inside the microresonator in active configuration. At the first, the existence of optical patterns in semiconductor microresonators in active configuration demonstrated then, the possibility of controlling these optical patterns using another light (All Optical Switching) has been studied.

We propose a new method of minimizing the gain-transient recovery time of wavelength-division-multiplexing (WDM) signals in cascaded erbium-doped fiber amplifiers (EDFAs) in WDM network as the gain of signals in EDFA fluctuates due to channel add/drops. To minimize the gain-related errors at the receivers, the gain of the signal should be recovered back to its original level as fast as possible. In this paper, we have applied, for the first time in our knowledge, the wellknown control theory of disturbance observer technique to the control of gain-transient recovery of cascaded EDFAs. We have used a disturbance observer to detect and compensate the gain variations due to WDM channel add/drops. While the major compensation of the gain is performed by the disturbance observer, the fine control process for exact gain recovery is done by a proportional/integral/differential (PID) controller. The proposed gain control algorithm for EDFA was implemented by MATLAB and the performance of the technique was verified by simulations for the cases of different numbers of cascaded EDFAs in WDM networks. For simulation, we have used a commercially available numerical modeling software package such as the Optsim^TM. Simulation results show that the technique decreases the amount of gain-transient recovery time to less than 3μsec in all the cases. This amount of gain recovery time is just about 1% of the one for commercial WDM EDFAs in these days.

We propose a paraxial solution for pixel shift selectivity, which can simulate the pixel shift selectivity in two dimensions and in wide range easily. Thus, the effect of different reference patterns can be calculated in detail. From the simulation result, we conclude that the pixel shift selectivity get worse for amplitude modulation reference patterns. Making no modulation is the best reference pattern for pixel shift selectivity, however the point spread function will be worst in this case. To get an optimum system in both pixel shift selectivity and point spread function, the reference pattern with phase modulation will be the best choice.

Single-mode propagation conditions of X-ray waveguides are investigated by numerical calculations to understand the dependence of waveguide design parameters, such as core thickness and the optical constants of waveguide materials, on the transmission and coherence properties of the waveguide. The simulation code for mode analyzing is developed based on a numerical solution of the parabolic wave equation. The initial boundary value problem is solved numerically using a finite-difference scheme based on the Crank-Nicolson scheme. The E-field intensities in a core layer are calculated at an X-ray energy of 8.0 keV for air and beryllium(Be) core waveguides with different cladding layers such as Pt, Au, W, Ni and Si to determine the dependence of waveguide materials. The highest E-field intensity radiated at the exit of the waveguide is obtained from the Pt cladded beryllium core with a thickness of 20 nm. However, the intensity from the air core waveguide with Pt cladding reaches 64% of the Be-Pt waveguide. The dependence of the core thickness, which is the major parameter used to generate a single mode in the waveguide, is investigated for the air-Pt, and Be-Pt waveguides at an X-ray energy of 8.0 keV. The mode profiles at the exit are shown for the single mode at up to a thickness of 20 nm for the air-Pt and the Be-Pt waveguides.

A planar photonic crystal waveguide (PCW) is an essential component of a photonic integrated circuit. For a given guided mode, a PCW can be modeled by an equivalent transmission line. Electrical modeling of a PCW and its defect can help using circuit theory for designing photonic crystal circuits. The ratio of electric and magnetic field (called the wave impedance), weighted by the Poynting vector for an infinitely long PCW, can serve the purpose of the characteristic impedance of the transmission line. FDTD method is employed to compute the wave impedance of PCW. The characteristics of a square lattice PCW with dielectric pillars of refractive index 3.4, placed in two different dielectric substrates of refractive indices 1 and 1.45 respectively are investigated here. Investigation of a point defect created by placing a rod in the waveguide shows that depending upon the size and location, a point defect can be inductive or capacitive.

The accuracy of built-in-type encoder with an external diameter of 180 mm that is offered by the world leaders doesn't exceed ±2.5 angular seconds. A high accuracy angular built-in-type encoder with error about ±0.3 angular seconds for laser images generators is shown in this paper. An angle encoder was made using 165 mm raster that had error equal to ±1.1 angular seconds. The error spectrum had evident predominance of second harmonic. This peculiarity predetermined choice of encoder configuration with four reading heads. The encoder emulation result had predicted encoder error no more then ±0.25 angular seconds. Resulting error of virtual encoder was determined by summary contribution of 4, 8, 12 and 16 harmonics. An encoder resulting error was determined by special angle measuring test bench. Error of real encoder didn't exceed ±0.35 angular seconds. The error spectrum had both expected 4, 8, 12, 16 harmonics and unexpected 2, 3, 5, 7 ones. The difference between the results of emulation and experiment is analyzed in this paper. The problems of creation of angle measuring test bench with error no more than ±0.1 angular seconds using ROD-800 angle encoder (which has accuracy only ±1.0 angular seconds) have been discussed.

It is shown that by properly using the geometrical optics approximation it is possible to design particular optical structures able to shape an optical beam in some wanted way. We discuss the application to hide to an incident plane wave, objects contained in a finite space region.

We study the light scattering properties of random media which have the refractive index distribution of threedimensional (3D) clipped laser speckle structures. To evaluate the performance of the speckle media as random laser cavities, we calculated the energy density and the local quality factor inside the media by means of the 3D finite difference time domain (FDTD) method. It is shown that the random media fabricated with the use of three speckle waves superposed without interference have the scattering strength as large as that of particulate media used conventionally for random laser media. To realize the speckle random media, we employed a technique of holographic lithography and fabricated polymer random media by illuminating photopolymer with one or two speckle waves. The far field scattering pattern of the sample media was measured to estimate the refractive index distribution of the samples. The experimental results suggest that a fibrous index structure, which is characteristic of 3D speckle patterns, is formed inside the sample media.

This article describes design of the photonic receiver composed of the system polymer planar waveguides, InGaAs p-i-n photodiode and integrated HBT amplifier on a low loss composite substrate. The photonic receiver was the main part of the hybrid integrated microwave optoelectronic transceiver TRx (transciever TRx) for the optical networks PON (passive optical networks) with FTTH (fiber-to-the-home) topology. In this article are presented the research results of threedimensional field between output facet of a optical waveguide and p-i-n photodiode. In terms of our research, there was optimized the optical coupling among the facet waveguide and pi-n photodiode and the electrical coupling among p-i-n photodiode and input of HBT amplifier. The hybrid planar lightwave circuit (PLC) of the transceiver TRx will be composed from a two parts - polymer optical waveguide including VHGT filter section and a optoelectronic microwave section.

In this paper, the simulations of the reflectance of the apodized and chirped Fiber Bragg gratings (FBGs) are presented. The reflectances of apodized FBGs with different modulations of the refractive index were simulated. The results show that reflected light is concentrated to the main reflectance line with negligible sidelobes. Simulations of linearly chirped FBGs show that sharp reflectance lines can be achieved which makes this kind of FBGs suitable candidates for wavelength multiplexing/demultiplexing.

We present the simulation method to calculation of arbitrary fiber grating (apodized, chirp etc.) with high precision by combination of methods based on layered dielectric media (LDM) and transfer matrix. On the contrary to the other calculation techniques the LDM method is based on sequence of thin films of dielectric media assembled in the direction of wave propagation. The critical parameter of fiber gratings, the bandwidth can be narrowed by higher refractive index change, longer gratings or by multiplying fiber gratings. On the basis of our simulations and measurements of the commercially available fiber gratings we designed a special 100 mm long fiber Bragg grating with apodization. Finally, we simulated parameters of fiber gratings arrays-multiple fiber gratings. We expect the application of FBGs to improvement of the linewidth and mode-hop free tuning range of semiconductor lasers at the wavelength 760 nm to increase resolution of fiber laser interferometer based on these laser diodes.

Recently, optical fibre tapers have intensively been investigated for many applications e.g. in telecommunications, medicine and (bio-) chemical sensing. The paper deals with enhancement of evanescent-field sensitivity of the solid-core microstructured fibre with steering-wheel air-cladding. Enhancement of a performance of the microstructured fibre is based on reduction of fibre core diameter down to narrow filament by tapering thereby defined part of light power is guided by an evanescent wave traveling in axial cladding air holes. The original fibre structure with outer diameter of 125 µm was reduced 2×, 2.5×, 3.33×, and 4× for increasing relatively small intensity overlap of guided core mode at wavelength of 1.55 μm with axial air holes. The inner structures of tapered microstructured fibre with steering-wheel aircladding were numerically analyzed and mode intensity distributions were calculated using the FDTD technique. Analyzed fiber tapers were prepared by constructed fibre puller employing 'flame brush technique'.

This paper deals with Photonic Crystal Fibers (PCF) that is not sensitive to bending. On one hand, fiber bending may result in potential negative chromatic dispersion or coupling light from the fundamental mode into the cladding modes, which opens many possibilities to design microstructured optical components for all-optical PCF-based system (group velocity dispersion compensator, bending-induced zero-dispersion fiber, optical filter, optical switch, coupler, photonic crystal cavity with electromagnetically induced transparency etc.) On the other hand, fiber bending is responsible for huge bending losses. The goal of this paper is to reduce bending losses in an operating range of the designed fiber. Reduction of bending losses could be considered as an optimization of the structure that exhibits negative chromatic dispersion and low losses concurrently - then the component is utilizable for many specific applications as dispersion compensator or as an optical switch. Another approach is to design the fiber that would be single-mode for wide range of bending angles or bending radii, but the light is not being coupled into the cladding. Then, no negative chromatic dispersion is produced and the fiber works as a conventional PCF, but not sensitive to bending in an office environment.

The electromagnetic wave propagation between two media characterized by the permittivity and permeability and the transport of ballistic electrons with different effective masses across the heterointerface are investigated. The analogy of Snell law for ballistic electron is discussed; the existence of the critical angle of incidence is related to the electron energy and quasiimpuls conservation and to the effective barrier height. The quantum mechanical formulae for transmission and reflection of ballistic electrons with different effective mass at the heterointerface and Fresnel formulae for electromagnetic wave at the interface between media with different permeabilities are compared. The reflectance of electrons can be zero under certain conditions and their transmittance is equal to unity; this effect can be considered as an analogy of Brewster angle for electromagnetic waves. The existence of metamaterial for electron waves is discussed.

Conically tapered fibers with dielectric or metalized waists or tips of a sub-wavelength diameter have the potential of a range of applications, from optical probes for near-field detection to (bio)chemical sensing in extremely small volumes of analytes. For successful design, a robust modeling tool is a prerequisite. In such structures, strongly lossy modes with complex propagation constants with large imaginary parts may be excited. In this paper, a reliable eigenmode solver for cylindrical structures containing metal layers is described. An analytical function whose roots correspond to propagation constants of waveguide eigenmodes is formulated. Its roots are found with a help of Argument Principal Method. Due to the analyticity limitation, the waveguide structure has to be of a finite diameter with either electrically or magnetically conductive walls. The approach is implemented within the well-known modeling tool CAMFR. The feasibility of the method is demonstrated using the example of light propagation in the metalized fiber taper dipped in the surrounding medium.

Mid-infrared photovoltaic detector (PD) designed on the base of a type II p-InAs/p-GaSb asymmetric heterostructure with a deep AlSb/InAsSb/AlSb quantum well (QW) at the interface is reported. The heterostructures containing the single QW were grown by LP-MOVPE. Transport, electroluminescent and photoelectrical properties of these structures were investigated. Intense both positive and negative electroluminescence was observed in the spectral range 3-4 µm above room temperature (300-400 K). Spectral response in the mid-infrared range 1.2-3.6 μm was obtained at temperatures T=77-300 K. High quantum efficiency η=0.6-0.7 responsivity S_λ=1.4-1.7 A/W and detectivity D_λ* =3.5×1011 cm Hz^1/2w^-1 were achieved at 77 K. Such QW PDs are suitable for heterodyne spectroscopy and free space communication using quantum cascade lasers as well as for gas analysis and ecological monitoring applications.

We report about design and construction of the bidirectional transceiver TRx module for subscriber part of the passive optical network PON for a fiber to the home FTTH topology. The TRx module consists of a epoxy novolak resin polymer planar lightwave circuit (PLC) hybrid integration technology with volume holographic grating triplex filter VHGT, surface-illuminated photodetectors and spot-size converted Fabry-Pérot laser diode in SMD package. The hybrid PLC has composed from a two parts-polymer optical waveguide including VHGT filter section and a optoelectronic microwave section. The both parts are placed on the composite substrate.

A new spectral-domain interferometric technique used for measuring the group index of holey fibers over a wide wavelength range is presented. The technique utilizes an unbalanced Mach-Zehnder interferometer with a fiber under test of known length placed in one of the interferometer arms and the other arm with adjustable path length. First, the differential group index of the fiber is measured. Second, the fiber excitation is changed to guide light in the fiber cladding or the fiber is replaced by the reference sample of known thickness and known group dispersion to determine precisely the group index of the fiber at one specific wavelength. The group index as a function of wavelength is measured for two different holey fibers, one of them made of pure silica glass.

Photonic crystal and structural properties of synthesized opal films filled with the iron oxides: hematite (α-Fe₂O₃) and magnetite (Fe₃O₄) were investigated by means of scanning electron microscopy, X-ray diffraction, and Fourier transforme spectroscopy. Hematite was infiltrated into opal film pores without depositing the oxide onto the outer film surface by the method of lateral infiltration under capillary forces from a liquid precursor. The synthesis of Fe₃O₄ was performed in the opal pores using α→Fe₂O₃ as a precursor. The evolution of Bragg diffraction line from the (111) planes of the f.c.c lattice of the opal-α-Fe₂O₃ film with a various filling degree was studied. The maximum filling degrees both of opal- α-Fe₂O₃ and of opal-Fe₃O₄ films, estimated from the reflection spectra, appeared to be similar and equal to ~ 55% of the pore volume. The reversible chemical transformation of fillers in opal pores α-Fe₂O₃→Fe₃O₄→α-Fe₂O₃ changes only the filler dielectric constant but does not practically produce structural defects that could affect the photonic crystal properties of the composite.

We experimentally investigate effects of linear and nonlinear propagation of light beams within one-dimensional photonic superlattices fabricated in bulk photorefractive lithium niobate samples and in photorefractive planar waveguides by optical induction technique. In other case similar superlattices are formed by optical modulation of periodic waveguide arrays produced in lithium niobate by thermal diffusion of titanium and iron. The linear localization of light power is experimentally observed in superlattices of all kinds and proved using numerical simulations of light propagation within such structures. The features of nonlinear behavior of light at its propagation in superlattices is also experimentally demonstrated in a configuration of their single-channel excitation.

The properties of the natural modes in a dispersive stratified N-layer medium are investigated. Especially the focus is on the (over)completeness properties of these modes. Also the distribution of the natural frequencies are considered. Both the degree of (over)completeness and the natural frequency distribution turn out to be totally different from what is known for the non-dispersive case.

The band-structure properties of a photonic two-dimensional honeycomb lattice formed by cylindrical semiconductor shell rods with dielectric permitivities ε₁ and ε₂, and embedded in a background with permitivity ε₃, is studied by using an standard plane-wave expansion. The properties of bandgaps and density of states, considering dispersive dielectric responses, are investigated together with the possibility of fabricating systems with tunable photonic bandgaps, due to the Voigt magneto-optical effect, under the influence of an external magnetic field.

The photonic modes of Thue-Morse and Fibonacci lattices with generating layers A and B, of positive and negative indices of refraction, are calculated by the transfer-matrix technique. For Thue-Morse lattices, as well for periodic lattices with AB unit cell, the constructive interference of reflected waves, corresponding to the zero^th-order gap, takes place when the optical paths in single layers A and B are commensurate. In contrast, for Fibonacci lattices of high order, the same phenomenon occurs when the ratio of those optical paths is close to the golden ratio. In the long wavelength limit, analytical expressions defining the edge frequencies of the zeroth order gap are obtained for both quasi-periodic lattices. Furthermore, analytical expressions that define the gap edges around the zeroth order gap are shown to correspond to the < ε > =0 and <μ> = 0 conditions.

We report about fabrication and properties of Gallium Nitride (GaN) layers doped with erbium or mixture of erbium and ytterbium ions. Transmission spectra in the spectral range from 280 to 800 nm taken by the spectrometer Varian Cary 50 showed that the increasing concentration of the dopants shifts the absorption edge to the lower wavelengths. Optical band gap E_g was determined from the absorption coefficient values using Tauc's procedure and the obtained values varied from 3.08 eV to 3.89 eV depending on the erbium or erbium plus ytterbium doping. Photoluminescence emission at 1 530 nm due to the Er³⁺ intra-4f ⁴I_13/2 → ⁴I_15/2 transition was observed by using excitation of semiconductor lasers operating at 980 nm.

We investigate superradiant lasing in 1D photonic crystal taking into account both homogeneous and inhomogeneous broadening in a two-level active medium. The latter may be based on, e.g., the quantum-well heterostructures and the fibers activated by color centers where Bragg structure can be fabricated artificially by means of a periodic modulation of the cladding layers. The truncated Maxwell-Bloch equations for the counter-propagating waves, the polarization and inversion of an inhomogeneously broadened two-level medium are used to analyze numerically the interplay between the back-scattering, amplification, dispersion, and de-phasing of waves. It is found that, if the photonic band gap is less than the coherent amplification bandwidth, there is a wide range of the pumping and relaxation parameters of a two-level medium where superradiant lasing exists and results in generation of a quasi-periodic and/or chaotic series of powerful and short pulses similar to those of Dicke superfluorescence. It is the cavity mode selection due to distributed feedback caused by the resonant Bragg structure which is responsible for the existence of superradiant lasing. Typical parameters of superradiant photonic-crystal lasers, including lengths, photonic band gaps and relaxation rates, are indicated.

Our paper deals with the survey of currently exploited electron-beam technologies to produce several protective optical elements. The computer-synthesized security elements are recorded with a resolution reaching 500.000 dpi and are specially developed for the security of the most important state valuables and documents. We shall mention some principal features, where the ultra-precise recording of diffractive elements is exploited.

Holography, holographic interferometry, or holographic optical elements manufacturing are compromised by the shortcomings of used holographic recording materials. Classical materials such as silver-halide emulsions, their excellent sensitivity, resolution, spectral range are eclipsed by the necessity of wet chemical processing and by inherent noise. Other commonly used holographic materials are not much better, some of their parameters are good however compromised with other weak parameters. Recently, it has seemed that new properly designed and manufactured photopolymer recording materials can overcome most of these problems. The sandwich structure (glass-polymer-glass) of the recording media can be easily prepared from commercial available liquid photopolymers (Polygrama) and well balanced holographic recording media are obtained by this approach. This paper presents testing results and preliminary conclusions of sandwich photopolymer structures employed as a holographic recording media. Characterization of recording structures as well as real life holographic usage examples are done. Influence of development and hardening of photopolymer are shown. Innovative formula of used photopolymer enables easily to reach diffraction efficiency of structures close to 100 % with low dose of exposition energy.

This research proposed a new method HTGA (Hybrid Taguchi Genetic Algorithm) for extended optimization of 350X zoom optics with DOE (Diffractive Optical Element) in order to eliminate chromatic aberration efficiently. Thanks to negative Abbe number of DOE, the optimal eliminating chromatic aberration could optimized and minimized with DOE coefficient and glass material. Following the advanced technology applied to micro lens and etching process, precisely-made micro DOE element now is possible to be manufactured in a large number. The steady Taguchi method incorporated with the genetic algorithm (GA), called hybrid Taguchi-genetic algorithm (HTGA), proposed in this research, have reached success in determining the best position for DOE plane and conclusively eliminate the chromatic aberration of 350 Zoom optics with DOE element and various glass materials.

Humidity induced changes in the refractive index and thickness of polyethylene glycol (PEG) thin films are in situ determined by optical waveguide spectroscopy. PEG brushes are covalently attached to the surface of a thin gold film on a borosilicate crown glass (BK7) using a grafting-from chemical synthesis technique. The measurements are carried out in an attenuated total internal reflection setup. At low humidity levels, both the refractive index and the thickness change gradually due to swelling of the PEG thin films upon water intake. At around 80% relative humidity, a steep decrease in the refractive index and a steep increase in the thickness are observed as a result of a phase change from a semicrystalline state to a physical gel state. The hydrogenation of PEG films causes a less pronounced phase change from a semicrystalline state to a gel state. Due to fewer ether oxygen atoms available for the water molecules to make hydrogen bonding, the polymer has a more stable structure than before and the phase change is observed to shift to higher humidity levels. It is discussed that such a humidity induced change in the index of refraction can be utilized in constructing of a PEG based humidity sensor.

A high sensitive temperature sensor based on evanescent field coupling between a side-polished fiber half-coupler (SPFHC) and a thermo-optic multimode overlay waveguide (MMOW) is designed and demonstrated. Such a structure essentially functions as an asymmetric directional coupler with a band-stop characteristic attributable to the wavelengthdependent resonant coupling between the mode of the SPFHC and one or more modes of the MMOW. A slight change in temperature leads to a significant shift in the phase resonance-coupling wavelength ( λ_r ) between the MMOW and SPFHC λ_r, which is easily measurable. The wavelength sensitivity of the device is measured to be ~ 5.3 nm/°C within the measurement range of 26-70°C; this sensitivity is more than 5 times higher compared to earlier reported temperature sensors of this kind. The SPFHC was fabricated by selective polishing of the cladding from one side of a bent telecommunication standard single-mode fiber and the MMOW was formed on top of the SPFHC through spin coating. A semi- numerical rigorous normal mode analysis was employed at the design stage by including the curvature effect of the fiber lay in the half-coupler block and the resultant z-dependent evanescent coupling mechanism. An excellent agreement between theoretical and experimental results is found.

Microstructured optical fibers have much more degrees of freedom concerning the geometries and index contrasts than step-index fibers. This richness opens totally new fields of application for fiber optics. The finite element method appears as an extremely versatile tool to compute the propagation modes in such systems as it allows to take into account arbitrary geometries of the cross section and also anisotropic and inhomogeneous (i.e. not only piecewise constant) dielectric permittivities. In this paper, we review some more advanced features: how to compute leaky modes (crucial for the understanding of such kind of fibers) by using perfectly matched layers, how to use helicoidal coordinate systems to determine the influence of a twist on the modes via a two-dimensional model (using equivalent materials), and how to compute spatial solitons in fibers involving Kerr optical medium by taking into account the refractive index inhomogeneities caused by the nonlinearity.

Magneto photonic crystals exhibit unique combination of magneto-optical nonreciprocity and resonant behavior originating from periodic structure. Modeling of magneto photonic structures requires inclusion of magnetic induced anisotropy and description of medium using a permittivity tensor. On the other hand, differential theory of periodic gratings based on Fourier expansion of permittivity tensor and electromagnetic field is recently frequently applied. In this paper we propose an approach of effective propagation constant calculation from scattering matrix of the waveguide consisting of the anisotropic magneto-optical lamellar grating. The structure is modeled using Rigorous Coupled Wave Analysis (RCWA) extended by Fourier factorization method. The approach is applied to optimize parameters of integrated magneto-optic waveguide isolator with lamellar grating from magneto-optic medium at transverse geometry.

Silica-based thulium-doped fibers sensitized by ytterbium are being developed for applications in fiber amplifiers and lasers at various wavelengths (around 800 nm, 1470 nm and 2 µm). Several studies have been performed to design and optimize thulium- and ytterbium-doped fiber (TYDF) amplifiers and lasers at the above mentioned wavelengths. Although some papers dealing with modeling of such a system exist, the parameters used in the simulations, like energy transfer coefficients, have not been experimentally determined to date. In this paper we present an estimation of the energy transfer coefficients by comparison of the measured emission of three TYDF samples with numerical simulations of the respective emission using a spectrally and spatially resolved model of TYDF. We found that the energy transfer coefficients are higher than those reported in Tm/Yb-doped fluoride based crystals. This fact together with the possibility of increasing the energy transfer efficiency, by improvement of excited level lifetime of thulium by high alumina codoping, makes thulium/ytterbium co-doped silica fibers promising for applications in fiber lasers and amplifiers.

Time-domain interferometry (TDI) is a well-established measurement technique that can be used for the characterization of either optical devices or pulses. Conceptually, TDI needs a variable-delay interferometer for evaluating the crosscorrelation between an optical signal propagating through an optical device and a reference field undergoing a controllable delay. In this contribution, a simple and flexible phase-sensitive interferometric setup combining two different TDI schemes is presented. The first scheme, employing a broadband optical source, implements an optical lowcoherence interferometry (OLCI) system, which enables an accurate frequency-domain characterization of generic optical devices. In the second scheme, referred to as optical coherence pulsed interferometry (OCPI), a pulse modulated coherent source is used to observe in time-domain the propagation of optical pulse through optical devices, providing a direct observation of the true-time delay and the envelope distortion experienced by the pulse. The two techniques are implemented on the same interferometric setup and can be combined to achieve a full time-domain and frequencydomain characterization. Some examples concerning the characterization of integrated coupled ring-resonators devices are presented and compared with alternative measurement techniques.

Formation of dark spatial optical solitons in planar waveguides produced by implantation of light ions into Fe- or Cudoped X cut lithium niobate wafers is experimentally studied. The implantation both of protons and O³⁺-ions results in the excellent waveguide layers with their thickness about 3 microns and optical losses less than 1 dB/cm. The soliton states at light wavelengths of 532 nm and 633 nm are developed due to the self-defocusing photorefractive-photovoltaic nonlinearity of lithium niobate. Extraordinarily polarized light beams are used in experiments to form dark solitons and to probe the soliton-induced waveguide channels. Steady-state dark photovoltaic spatial solitons have been realized in both, H⁺- implanted and O³⁺ - implanted planar waveguides at optical powers from 10 to 100 microwatts. The storage time of soliton-induced channel waveguides makes up at least some hours without special illumination of a planar waveguide and they may be erased within some seconds in a case of their permanent readout with stronger light beams. The possibility to form more complicated channel waveguide structures in regimes of dark spatial solitons is also demonstrated.

Supercontinuum sources generated by continuous-wave excitation are very promising for many applications as they present in general higher spectral power density then their pulsed counterparts. On the other hand, the properties of supercontinuum are very difficult to be controlled as the initial broadening is driven by modulation instability. This latter one breaks-up the CW radiation into a train of ultra-short pulses whose peak power, spectral length and shape strongly depend on the power, coherence and noise of the pump and on the fiber properties. In this paper, we present a preliminary work on the role of chromatic dispersion on supercontinuum spectral broadening in order to study how to optimize SC spectral width under CW regimes. By means of a home-made tunable high-power laser we induce supercontinuum generation by pumping at different dispersion values of the fiber. We show that at low injected powers the wider spectrum is obtained when pumping just above the zero-dispersion wavelength of the fiber. By contrast, for higher injected powers, wide and squared-shaped spectra can be obtained when pumping over a larger range of anomalous dispersion values. These results seem to be very promising for a number of applications requiring smooth, squared and high-power SC spectral profiles such as optical coherence tomography.

Operation of a diode-end-pumped double-clad planar waveguide Nd:YAG laser is reported. The waveguide structure consisted of 220 μm thick active Nd:YAG layer sandwiched between two 390 μm undoped YAG layers. The outer cladding was formed by two 200 μm sapphire layers. Dimensions of the whole structure are 12 × 6 × 1.4 mm³. With pumping by 2 W laser 808 nm diode, the laser operation was achieved at 1.06 μm with several resonator configurations: plan parallel resonator with external mirrors, self-imaging resonator, and resonator with mirrors coated on waveguide structure faces. In multimode operation the slope efficiency was 58%. The maximal output power of 640 mW was achieved. In single mode operation with self-imaging resonator the slope efficiency of 34% was achieved. With mirrors coated directly on waveguide structure faces the slope efficiency of 49% in single transversal mode was obtained.

Optical CDMA is a flexible technology for efficient and scalable multiple access networks. It also offers increased physical layer privacy and on-demand bandwidth sharing management. Highly scalable approach to incoherent OCDMA system was developed and demonstrated. Error-free operation with a BER less than 10^-12 including complete elimination of the MAI noise was achieved using 2ps time gating. The approach introduces a negative power "penalty" which helps to improve an overall system power budget and performance. It is shown that two picosecond time gate can significantly improve number of simultaneous users in the system by more than tree times without any degradation of BER.

We experimentally demonstrate soliton self-frequency shifts well-beyond 500 nm in suspended core fibers. We compare two fibers and show that the dispersive wave generation induced by the presence of a second zero dispersion wavelength or the OH-absorption peak may limit the soliton shift performance. By measuring the frequency stabilization spectrum of the shifted soliton, we show that we can simply and accurately evaluate the second zero dispersion wavelength.

The goal of our work is the development of intracavity synchronously pumped optical parametrical oscillator (OPO), generating two trains of picosecond pulses inside a single cavity. These trains have the same repetition rate but they are independent and can differ in phase and carrier frequency. They can interfere on a detector, producing a beat note at the carrier frequency difference. This allows to determine very precisely the phase difference between them which is possible to use in all sensor applications where the measured physical quantity is converted into phase difference between two counter-circulating pulses. We designed a synchronously pumped OPO with nonlinear crystal (MgO:PPLN) for parametric generation inserted inside a linear resonator of a modelocked diode pumped Nd:YVO₄ laser. This configuration ensures the same way for signal and pumping waves through the crystal and reduces the dead-band of the beat signal. We observed that the OPO could generate in three regimes: the desired dual pulse operation when the pump pulse produces parametric waves during both forward and return passes through PPLN crystal. Two single pulse OPO operations are possible when parametric interaction occurred only during one pass of the pump pulse through the PPLN crystal in forward or backward direction.

Eye-pattern diagrams confirmed a negative feedback effect was generated by the band pass filter in the module. The negative feedback effect is able to recover signal loss to a far higher definition and a much lower error probability. The modulation degree ratios of the module with negative feedback also appeared to have optical characteristics of a higher fidelity and a more stable baseline. All of our results confirmed the fact that the module induces a negative feedback response. The all-optical triode equipped with the module was functional at a control power range of 0.01 to 1 mW.

We report efficient generation of high energy femtosecond pulses in the near-IR using a two stage, white-light seeded femtosecond optical parametric amplifier (OPA). The OPA, based on two 3-mm crystals of BiB₃O₆ and pumped at 807 nm by a 1 kHz Ti:sapphire laser amplifier can provide femtosecond signal pulses over the 1150-1450 nm range. Frequency resolved optical gating measurements result in near-transform-limited pulses with durations down to 27-fs for 200-fs pump pulses corresponding to more than 7 times pulse shortening.

We theoretically investigate the propagation of a one-dimensional (1D) polarized light beam in cubic photorefractive crystals of 23 symmetry group. Light beam propagation was considered under condition applied to the crystal external electric field for increasing the photorefractive response. Within paraxial approach we obtain the self-consistent system of equations for scalar amplitudes of two optical eigenmodes and the photoinduced space charge field. We have shown that the natural circular and induced by external and internal electric field linear birefringence determine the character of transformation of the spatial structure of the beam. For transverse optical configuration of the crystal sample and length of light waves λ = 633 nm we demonstrate that in a crystal the Gaussian light beam is splitted into two beams. That beams spread symmetrically relative to the normal to the entrance edge of the sample. A feature of this process is the soliton formation in each of that beams. Process of spatial soliton formation is accompanied by scattering of light energy. The solitons cross-size a lot less than the width of the incident Gaussian beam, which was 30 micron in our calculations. Under such conditions soliton eigenmodes is formed in the BS0 and BT0 crystals with non-local photorefractive response.

The impact of temperature, incident light polarization and a weak external magnetic field upon the conditions of optical bistability (OB) realization in the exciton absorption region of layer semiconductors has been investigated. With the 2Hpolytype PbI₂ used as an example, the possibility of obtaining the OB realization region by changing the external factors has been shown. It has been also demonstrated that the change of these parameters can control the position and values of the absorption hysteresis loop of corresponding layer crystal excitation exciton zones.

In this work, we present optimized rib-type and photonic crystal based horizontal slot waveguide structures which provide the possibility of electrical wiring while at the same time maintaining minimum mode volume for linear and nonlinear applications.

Spectral dependencies of the optical properties of Ge-As-S films were obtained from the transmission spectra by modified Swanepoel method. The results for optical parameters were analyzed using single oscillator model. Film thickness, d, optical band gap, E_gopt, oscillator energy E₀, and dispersion energy, E_d, before and after exposure to light were determined. Non-linear optical properties were estimated by means of generalized Miller's rule and classical anharmonic oscillator model.

Nonlinear optical properties of GaAs/(AlGa)_XO_Y heterostructures using interband excitation by 150 fs laser pulses is reported. A considerable wideband nonlinear response is observed. Mean decay time for nonlinear reflection in heterostructures ranges from 1.5 to 3.5 ps. The shift of the GaAs energy-band structure caused by the high tensions in GaAs/(AlGa)_XO_Y structure is observed.

The paper deals with elimination of defocusing and thermal noise out of black & white pictures captured by a CCD/CMOS camera with imperfectly adjusted lens. For purposes of image recovery we can use the MAP criterion based iterative detection network (IDN) containing a number of mutually concatenated functional blocks so-called soft inversions (SISOs). This cellular structure makes IDN suboptimal but also numerically very simple and practically applicable in contrast to an unviable optimal (single-stage) MAP detector. Firstly we focus closer on SISO entities and consequently on the creation of entire IDN, specifically the so-called distributed IDN marginalizing at the symbol level. In the end, image reconstruction example will be presented (using this type of IDN) along with its performance characteristics (BER curves) for various levels of defocus.

This paper deals with an image compression algorithm based on the three- dimensional Karhunen- Loeve transform (3D KLT), whose task is to reduce time redundancy for an image data. There are many cases for which the reduction of time redundancy is very efficient and brings perceptible bitstream reduction. This is very desirable for transfering image data through telephone links, GSM networks etc. The time redundancy is very perceptible e.g. in camera security systems where relative unchanging frames are very conventional. The time evolution of grabbed scene is reviews according an energy content in eigenimages. These eigenimages are obtained in KLT for a suitable number of incoming frames. Required number of transfered eigenimages and eigenvectors is determined on the basis of the energy content in eigenimages.

The third order optical aberrations models for LSI/LSV (Linear Space Invariant/Variant) systems is described in this paper. These models are based on Seidel and Zernike approximating polynomials. Optical aberrations effect to the PSF (Point Sread Function) of optical imaging systems is described as well. Higher quality and precision of image data can be obtained with deconvolution of the acquired images and system point spread function. The PSF can be modelled as a space variant function from the estimation of optical system wavefront aberrations.

A motional array of optical traps created by interference of two counter-propagating waves can be used for particle delivery. The mean particle speed is affected by jumps between neighboring traps and is always lower than the velocity of the trap array. We show that a significant enhancement of the delivery speed can be obtained if several particles are delivered simultaneously. We speculate that optical binding between particles and hydrodynamical drafting cause this speed enhancement.

The radiative decay rates of perylene dye molecules, attached to silicon nano-rods are investigated by means of timeresolved fluorescence experiments. The decay rates of dye molecules in the vicinity of silicon nano-rods are inhibited due to their various diameters and therefore the modification of the surrounding environment. Inhibition is caused by an increased nonradiative rate due to resonant energy transfer described by the Gersten-Nitzan model.

Nanoimprinting provides an alternative approach for production of highly ordered arrays of nanostructures on a wafer scale cheaply and rapidly. Disposable master technology is a promising method for creating large-area sub-wavelength photonic elements, solar cells and PhC structures. The geometrical parameters of the surface profile of disposable master samples and its replicas in the nanometer scale can be determined by applying standard methodology of the surface morphology measurement by AFM or SEM. Systematic studies will be focused on the process control for pattern transfer into different types of resist and its homogeneity on Si wafers. In particular, using a single spent polymer mold, imprint results shows, that the conditions for spin coating and curing the resist determine the homogeneity and replication fidelity that can be achieved. To analyze structures over large areas the above techniques can be used for statistical sampling. In addition, the general uniformity of the materials will be assessed using large-scale optical techniques. For the visualization and testing of structure pattern homogeneity as well as the pattern defects identification a large field diffraction-based diagnostic method has been utilized. The results indicate that choice of processing conditions is, in addition to materials selections, extremely important in achieving high-fidelity nanostructures.

We present the first creation of extended longitudinally optically bound chains of microparticles in one dimension. Two counter-propagating "non-diffracting" beams, so called Bessel beams, were used to illuminate the submicrometer sized polystyrene particles immersed in water. Beam homogeneity and extended propagation allowed the creation of 200 microns long chains of organised micro-particles. Furthermore two types of multistability were observed: short range multistability within a single chain and a long-range multi-stability between several distinct chains. Our observations are supported by theoretical results of the coupled dipole method.

Recent experiments with Bose-condensate of indirect excitons in quantum-well traps in semiconductor heterostructures show long-scale coherence of recombination emission under appropriate CW laser pumping. We suggest that such coherence results from the existence of high-quality polariton modes, which are formed due to strong coupling of exciton polarization and electromagnetic field in a trap. These modes are of whispering-gallery origin and can be excited via stimulated emission of excitons supplied by the CW laser pumping. We analyze in detail the structure and spectrum of polariton modes taking into account polarization relaxation and radiative losses. We derive characteristic equation for mode wave-vectors and solve it numerically for the experimental parameters. The quality factors of a small number of modes are found to reach 10000 and higher. In the case of high density and narrow enough spectral linewidth of excitons, which could be achieved due to Bose-Einstein condensation, some modes become unstable giving rise to exciton lasing. We investigate their growth rates, instability thresholds, energy losses, and saturation amplitudes. Under typical experimental conditions, we indicate lasing polariton modes which can be responsible for the observed long-scale coherence of exciton emission.

At present superconducting detectors become increasingly attractive for various practical applications. In this paper we present results on the depelopment of fiber coupled receiver systems for the registration of IR single photons, optimized for telecommunication and quantum-cryptography. These receiver systems were developed on the basis of superconducting single photon detectors (SSPD) of VIS and IR wavelength ranges. The core of the SSPD is a narrow (~100 nm) and long (~0,5 mm) strip in the form of a meander which is patterned from a 4-nm-thick NbN film (T_C=10-11 K, j_C=~5-7•10⁶ A/cm²); the sensitive area dimensions are 10×10 μm². The main problem to be solved while the receiver system development was optical coupling of a single-mode fiber (9 microns in diameter) with the SSPD sensitive area. Characteristics of the developed system at the optical input are as follows: quantum efficiency >10 % (at 1.3 μm), >4 % (at 1.55 μm); dark counts rate ≤1 s^-1; duration of voltage pulse ≤5 ns; jitter ≤40 ps. The receiver systems have either one or two identical channels (for the case of carrying out correlation measurements) and are made as an insert in a helium storage Dewar.

We present a novel concept of photon number resolving detector based on 120-nm-wide superconducting stripes made of 4-nm-thick NbN film and connected in parallel (PNR-SSPD). The detector consisting of 5 strips demonstrate a capability to resolve up to 4 photons absorbed simultaneously with the single-photon quantum efficiency of 2.5% and negligibly low dark count rate.

This paper presents the results of our experimental study of high resolution map of induced photocurrent in monocrystalline silicon solar cells. Photovoltaic solar cells are evaluated by Near-field Optical Beam Induced photocurrent (NOBIC), as well as by Scanning Near-field Optical Microscope (SNOM) topography and reflection. The correlation between reflection and transport characteristic indicates possibility of this diagnostic tool. Therefore the SNOM and NOBIC represent the coupling of very useful methods to provide a non-destructive local characterization on silicon semiconductor solar cells.

This review summarizes the recent progress in the development of light emitting diodes (LEDs) and their application that have been reported. New types LED's will become possible by the use of inorganic and recently new organic semiconductors. The main goal in inorganic nitride based device technologies is to increase the performance above 100 lm/W and to use blue high brightness (HB) LEDs as a basic light source in high brightness white light devices. Organic LEDs are an interesting, prospective choice as a source of light for applications. Recent improvements have taken OLEDs to luminous efficiency greater than 20 lm/W, lifetime in excess of 10,000 hours and driving voltage of 5V and below. As LEDs continue to advance in brightness and efficiency, their effect on general lighting, automotive headlamps and television application could be significant to produce a huge impact on our future daily life.

Solid state lighting offers a lot of novel prospects for tomorrows customized lighting solutions. None the less, to compete with and to surpass the performance of the traditional lighting systems, design and development of LED light sources is still facing the necessity of further improvements, in particular with respect to device efficiency and light control. In this contribution we discuss recent developments and novel strategies in order to improve the light extraction efficiency as well as to affect the directionality of the light emitted from high power LEDs. In order to be up to characterize these modifications with high spatial resolution, novel characterization techniques, like the implementation of a confocal principle into the measurement set-up are discussed.

Today's most common approach for solid state lighting relies on the conversion of a portion of the blue light emitted from the LED die by an inorganic phosphor material. Although this concept, at a first glance, seems to be rather simple, the appropriate shape of the color conversion element (CCE) in white LED light sources turns out to have essential significance for the quality of the white light (especially in terms of angular homogeneity). In this contribution we discuss recent developments and novel coating concepts for LEDs that excel in terms of spatial homogeneity of the emission and variability of the color temperature, which on the one hand can be attributed to the application of Silicate based phosphors, a beneficial class of luminescent materials for LED application, and on the other hand on optimized CCE geometries, which were obtained by numerical calculations with the help of state-of-the-art simulation tools.

To achieve high luminescence white LEDs by UV excited phosphors, this research work presents theoretical results to demonstrate a novel white light LED structure and performance. The main purpose of our work is to solve two issues encountered, one is UV leak and another is low conversion efficiency of phosphors. A photonic crystal or an omnidirectional reflector (ODR) can be used to achieve this goal, as compared with a distributed Bragg reflector (DBR). The advantage of the ODR is that the UV light beam at any incidence can be omni-directionally reflected. In this study, a UV LED with a 380-nm wavelength with RGB phosphors and a photonic crystal with specific function were used. This novel white LED was constructed with an air gap between the phosphors layer and the ODR. Theoretical simulation study shows that the ODR will enhance the white light generation and prevent UV leak from the device. Theoretical simulation shows that a white light LED with an air gap located between the phosphors layer and ODR will have better performance than that without it. The simulation data shows that an ODR is the optimized way to reduce UV leak.

With their excellent photo-electronic properties, quantum dots, especially the II-VI family semiconductor quantum dots, are now widely used to photo- and electro-luminescence device such as inorganic and organic light emitting diodes recently. The quantum dots have many applications in optoelectronic device such as LEDs for its many superior properties resulting from the three-dimensional confinement effect of its carrier. In this paper, White light-emitting diodes (WLEDs) were fabricated by combining blue InGaN chips with luminescent colloidal core/shell CdSe/ZnS/CdS quantum dots (QDs). The core/shell/shell structural CdSe/ZnS/CdS nanocrystals were synthesized in aqueous solution by using mercapto-acetate as stabilizer. The double shell can improve the core/shell interface quality. Photoluminescence of CdSe/ZnS/CdS quantum dots demonstrated high photoluminescence efficiency with a quantum yield more than 45%, and size-tunable emission wavelengths from 490 to 610nm. WLED was successfully assembled by blue InGaN chip plus green and red emitting CdSe/ZnS/CdS QDs. The WLED had the CIE coordinates of (0.33,0.34) and color render index of 91. The InGaN chip white-light-emitting diodes with CdSe/ZnS/CdS quantum dots are potentially useful in general illumination and display applications.

We researched a new transparent concept display, transparent organic light emitting diode (TOLED) with new transparent cathode, Sr/Ag double layer. Sr is used as an electron injection material and Ag is adopted as a protective material for Sr and electrical conductor. This cathode has high transmittance over 70% at 520nm and low sheet resistance, about 12Ω/sq. We fabricated TOLED with two transparent electrodes, ITO and Sr/Ag. To improve device properties, transparent passivation layer, CsCl is deposited on transparent cathode. CsCl, passivation layer enhances the extraction of light emitting throughout the surface side of the TOLED by the improvement of transparency and the microcavity effect. TOLED without passivation layer shows the large difference of brightness as electrode, 26,700cd/m² and 10,000 cd/m² @14V through anode and cathode, respectively. However, CsCl makes to decrease difference between brightness through anode and cathode and come to similar brightness 20,600cd/m² and 18,200cd/m² @ 14V.

The fourth-order differential operator has been designed including its coefficients B_i and C_i in such a way, that its first three eigenfunctions Φ_i(λ_iΕ) are almost identical those obtained by orthogonalising the colour matching functions x(λ), y(λ), and z(λ), CIE 1964. This operator gives an exact description of colour perception. Any changes to the spectral sensitivity of the cone system and B_i, C_i coefficients in our mathematical model result in a description of colour blindness in the observer. The principal aim of this paper is to mathematically describe the above-mentioned operator.

The paper presents some laboratory problems relevant to application of coherent light during MSc study (programme Optics and Lasers). The attention is devoted to the coherent properties of laser diode module (LDM), which simultaneously gives an opportunity either to renew or introduce the basic principles of wave optics. A part of the paper, also, is dealing with a mathematical model developed, which can serve as a very illustrative and kind tool to get familiar with optical anisotropy, even if there are no experimental tools at hand. It is based on the interference phenomena of convergent polarized light and also takes into account the external electrical field attached to the crystal.

Optical communications offer a capable alternative to radio frequency (RF) communications for applications where high data-rate is required. This technology is particularly promising and challenging in the field of future inter-satellite communications. The term laser satellite communications (LSC) stands for optical links between satellites and/or high altitude platforms (HAPs). However, optical links between an earth station and a satellite or HAPs can be also involved. This work gives an overview of nowadays laser satellite communications. Particularly, it is focused on the factors causing degradation of the optical beam in the atmosphere. If an optical link passes through the atmosphere, it suffers from various influences such as attenuation due to absorption and scattering, intensity fluctuations due to atmospheric turbulence and background radiation. Furthermore, platform vibrations cause mispointing and following tracking losses. Suitable devices and used pointing and tracking system for laser satellite communications are discussed. At the end, various scenarios of the optical links and calculations of their power link budgets and limitations are designed. Implemented software is used for calculation of optical links. This work proves that the Free Space Optics (FSO) systems on mobile platforms, like satellites and HAPs are a promising solution for future communication networks.