The need to increase transmission capacity in communication networks is becoming very critical. This task can be accomplished by taking advantage of optical networks where techniques such as DWDM and OTDM are combined with the use of all-optical devices to help eliminate electronic bottlenecks. To fulfill these needs a new class of all-optical devices have been proposed and successfully demonstrated. By taking advantage of the nonlinear dynamics in semiconductor optical amplifiers in combination with optical interferometers new generation of ultrafast all-optical demultiplexers, data regenerators, wavelength, and data format converters have been developed.

Laser diodes became the most widespread lasers and now are available in a broad spectrum of wavelengths ranging from infrared to the visible region. The low power ones mainly those with the quantum well structure and gain or index guided configuration perform a narrow linewidth and soon became a favourite tool for interferometry and spectroscopy. The need for continuous tuning range led to the development Extended Cavity Laser systems (ECL) and Vertical Cavity Surface Emitting Lasers (VCSEL). Both systems seem to be promising laser sources for design of optical frequency standards or interferometric distance measurement devices. We present design of these laser systems and their applications in metrology of length.

The paper deals with parameters of image sensors, which are important for the image quality evaluation. The influence of the most important parameters upon image quality is investigated. Particularly the modulation transfer function, contrast, dynamic range, the influence of aliasing upon image distortion, sensor resolution, signal to noise ratio and detective quantum efficiency have been briefly reviewed. The most important parameter MTF was described in detail. The main goal was to find the suitable method for obtaining on 2D qualitative parameter - 2D MTF depending on sampling distance, sampling aperture and fill factor. At the end of this paper the influence of the 2D MTF from the point of image quality is evaluated via Matlab CCDSIM for the large area image sensors, used for medical application.

Interferometric measurement methods are based on the principle of interference of two coherent wave fields (object and reference) and consequent evaluation of the interference pattern. The measured quantity, e.g. deformation, is related to the optical path difference between both wave fields, which depends on the phase of the object wave field. The phase can be obtained from the values of the intensity of the interference field with phase measuring techniques. In the work there was proposed an optical method for measuring of static deformations based on the interference of coherent wave fields and phase shifting procedure. Detailed analysis of the measurement and evaluation process with respect to most important factors is performed.

Standard heterodyne interferometer can be used as phase modulation subsystem in a novel interferometer designed to measure the figure of projecting mirrors with 0.1 nm accuracy. This article discusses possible operational principles of the sensor and presents experimental results for fast sampling type sensor prototype.

This paper focuses on the technological aspects of an integrated wavefront sensor developed in the framework of standard CMOS technology. A wavefront sensor is used in Adaptive Optics to detect wavefront aberrations, which can be compensated by a deformable mirror. We use the Hartmann method and the sensor consists basically of two components: an opaque mask with apertures and an optical detector. Our main goals are compatibility with mainstream technologies and real-time operation. We briefly report on the performance of the sensor in open- and closed- loop.

We present angled-grating distributed feedback lasers (α-DFB lasers) with high beam quality and high output power of several Watts at the wavelength λ = 1060 nm. The spatial and spectral single mode emission of such lasers is achieved by a filtering mechanism due to repeated Bragg reflections at an angled grating. The influence of slant angle, coupling coefficient, electrode stripe width, length of the resonator, vertical wave guide structure, and facet coating were studied. For optimized structures we obtained a nearly diffraction limited beam with an output power of more than 1 W, a lateral far field divergence angle of 0.3°, a beam quality factor M² = 1.1 (M² = 3.2 @ 2.1 W), and a spectral line width less than 5.8 pm with 28 dB side mode suppression ratio.

This paper deals with some present methods of the photodetection of a human eye retina image and the following computer analysis of the obtained image dates. There are considered the detection and the computer quantitative evaluations of characteristic symptoms of glaucoma on the human eye retina. These symptoms and their numerical parameters, that are usually used, are shortly described. The main part of this paper describes the methods of the creation and the computer analysis of a three-dimensional map of the blind spot of the human eye retina (papila) and the adjacent area of the retina. The changes important for diagnostics of the above mentioned three-dimensional map are then detected through the computer analysis. Specially, the methods of scanning laser tomography and stereophotographic measurement of the mentioned part of retina are considered. Some concrete results ascertained by the mentioned methods are also shown. Lastly, our suggestions of methods of analyzing two-dimensional images of retina obtained by the colour fundus camera are shown.

Photoluminescence quenching response of as prepared and surface modified porous silicon sensors in presence of organic analytes in gas phase was studied. Surface modification aimed at increasing of operational stability and modification of sensoric response was performed by a hydrosilylation reaction with various organic compounds - methyl 10-undecenoate, haemin, cinchonine and quinine. These sensors were tested for a homological set of aliphatic alcohols from methanol to hexanol. We have systematically measured changes in porous silicon photoluminescence intensity as a function of concentration of detected analytes and evaluated sensitivity, detection limit and linear dynamic range of our sensors. Speed of the sensoric response was of the order of seconds. The obtained sensoric parameters were correlated with chemical and physical properties of both the compounds used for derivatization and the detected analytes.

Technological processes including laser welding that use a laser beam are typically accompanied with the occurrence of laser-induced plasma. This physical phenomenon is investigated by many different monitoring methods and optical emission spectroscopy is the most common. The recent advert of miniature fibre optic spectrometers and relative cheap and powerful computers has provided a very promising tool for on-line spectral analyzing of laser-induced plasma. The contribution deals with the on-line monitoring of a laser-induced plasma during laser beam welding by optical emission spectroscopy. In this study a continuous-wave CO₂ laser with output power up to 3 kW was used. Circumstances of partial and full penetration of welded specimen material and the relation with spectroscopic parameters of laser-induced plasma were investigated.

The system employs a spatial light modulator (SLM), between a pair of crossed polarizers, and an electronic shutter. Transmission of the SLM with the polarizers is controlled by graphical software that defines which pixels are fully transparent and which are fully opaque. While a particular binary graphics is on the SLM the electronic shutter allows light to pass for a certain time. The graphics is imaged, by an objective, onto a photoresist plate. A mercury lamp is used as a light source. The graphics changes after each exposition and the whole sequence of images determines the resultant surface-relief modulation.

Electroluminescent study of heterolasers based on vertically coupled self-assembled quantum dots has been done. Luminescent parameters were measured in the 77 ÷ 300 K temperature range. Lasing via ground state of quantum dots up to room temperature has been shown. Temperature independence of the electoluminescent peak position, which corresponds to the second excited state in quantum dots, has been explained.

In the paper the sensitivity of polymer-clad silica (PCS) fibers to changes of light-absorption coefficient in the evanescent-wave area are investigated both theoretically and experimentally. The theoretical analysis was carried out on the basis of a ray-optic model taking into account changes of the complex refractive index of the fiber cladding. Values of the complex refractive index estimated from spectral and refractive-index measurements with water/glycerol solutions of methylene blue were used in the analysis. Results calculated for the excitation of the fiber from axial light sources or by using inclined beams are shown in the paper and compared with experimental results.

Spectral-domain white-light interferometric technique with channeled spectrum detection is used to measure characteristics and parameters of a fiber optic spectrometer. In the experimental setup comprising a white-light source, a Michelson interferometer and a spectrometer to be characterized, the spectral interferograms are recorded for different optical path differences (OPDs) between interfering beams. By processing the recorded spectral interferograms using discrete filtering and fringe amplitude demodulation method, the spectral fringe visibilities, first as a function of wavelength for given OPDs between interfering beams, and second as a function of the OPD between interfering beams for given wavelengths, are obtained. It is confirmed, in accordance with previous experimental and theoretical results, that the spectral fringe visibility functions, which are dependent on the OPD between interfering beams, are Gaussian functions. From the widths of the Gaussian visibility functions the spectrometer bandpasses at different wavelengths are evaluated.

This paper presents method for facets passivation of high power lasers GaAl As using thin films of AIN and GaN formed by reactive sputtering at low temperature. GaN has been chosen due to its exceptional stability at high temperatures and resistance against attack. GaN is insoluble in acids. Layers of GaN protect AIN coating against influence of chemical and physical factors. We report some problems concerning technology of GaN thin films deposition using RF Sputtering from Ga target in Ar-N₂ gas mixtures. Observation of N⁺ peaks in plasma spectrum provides information on optimal conditions for synthesis of GaN. The quality of GaN layers was examined by X-ray Diffraction (XRD), SIMS method, optical absorption, measurement of refractive index and density. Lasers diodes with coated mirrors of AIN-GaN exhibit good stability during CW life-test.

A method of high power (AlGa)As laser mirrors passivation with thin AIN layers deposited by low temperature reactive sputtering is presented. In SQW-SCH laser diodes (LDs) with high optical confinement the optical power densities at the mirrors are very high, leading at some power level to so-called catastrophic optical damage (COD) of the mirrors (and lasers). Thus the COD level limits the LD’s optical output and to improve it, mirrors are usually protected with dielectric coatings, such as SiO₂, Si₃N₄ and Al₂O₃ layers. Here, the AIN layers are proposed as a LD mirror coatings because of their unique features including high smoothness and thermal conductivity (3.19 Wcm^-1K^-1) which is close to that of copper (4.01 Wcm^-1K^-1). Moreover thermal expansion coefficient of AIN matches well coefficient of GaAs. Single AIN layers (approx. λ/4 thick) have been deposited as front, low reflectivity LD coatings and for the rear, high reflectivity mirrors the AIN-Si λ/4 layer stacks (4 pairs) have been used. LDs with such coatings exhibit twofold external quantum efficiency and good stability during CW life test.

The peak power of 0.65 MW and energy of 1.9 mJ at 1572 nm-wavelength was demonstrated in a singly resonant diode pumped intracavity optical parametric oscillator (IOPO). The energy of 4.3 mJ in fundamental mode at 1064 nm-wavelength with 15 ns-pulse duration in passively Q-switched regime was achieved in the arranged for IOPO Nd:YAG slab laser pumped by 300 W quasi-cw diode array. The KTP crystal, size of 20×5×5 mm³, 'x-cut' for non-critically phase-matched parametric generation at the signal wavelength of 1572 nm was used in experiments. In optimized, with respect to single pulse energy, IOPO cavity with output coupler of 50% transmission at signal wavelength the five-fold shortening of signal pulse duration with respect to 1064 nm pump radiation was observed. The twice-higher level of signal peak power of 650 kW, compared to pump laser at 1064nm in the same cavity without OPO, was achieved. The conversion efficiency of 44% with respect to 1064 nm pump beam and 3.8% with respect to diode pump energy was demonstrated.

The submitted paper is devoted to a description of relevant experience with an implementation of optical JTC (Joint Transform Correlation) processing technique in two selected security applications - fingerprint and face recognition. It summarizes a long time testing of the above mentioned technique under various conditions and effects appearing frequently in real applications. The JTC configuration is a very well known optical scheme for a 2D correlation calculation that is widely used for identification and classification purposes in image databases. The optical hardware provides a fast and massively parallel performance with large computational power required by the 2D image correlation. The performance of a real setup exhibits some shortcomings caused by expected initial distortions and artifacts in the image. The numerous distortions have been tested such as zooming, deformation etc. relevant for real samples of fingerprints and faces and some results are summarized here and presented in comprehensive diagrams.

The proposed method is based on the law of reflection and can be used for large reflective continuous surfaces, which behave approximately as a deformable mirror of a general type. For successful application of the ray method for deformation measurement is crucial the reflectivity of the surface. If the measured surface is optically rough, then the light is diffusely scattered in different directions relating to the microstructure of the surface, and the described method cannot be used. To limit the influence of the surface roughness the plastic reflective foil can be affixed on the test surface. The research was focused on several theoretical and experimental aspects of evaluation of the deformations with the ray method, especially on problems of measuring extended objects in engineering practice and automatic process for evaluation of deformations.

Operation of laser diode and flash lamp pumped Nd:YAG lasers mode locked with two different types of semiconductor saturable absorbers is reported. In the first type that is used mainly in diode pumped systems the absorber layers are integrated on highly reflective Bragg mirror. The second type is for use in transmission mode inside the resonator. Different design of semiconductor elements, pumping geometries and resonator configurations were investigated and characteristics of laser operation in mode-locked regime are presented.

Operation of laser diode pumped Cr:LiSAF laser in 1 m long V-resonator with pump-threshold as low as 650 uW is reported. This threshold was observed simultaneously with threshold of single stripe (width of 50 um) 670 nm laser diode used as a pumping source.

Fibers with inverted-graded index (IGI) profiles in the core with all refractive-index values above that of silica were drawn from performs doped in the core with germanium oxide which were prepared by the MCVD method. The sensitivity of the fibers to refractive-index changes of the optical cladding was theoretically determined on the basis of measured refractive-index profiles by using ray optics and assuming axial excitation of the fibers. The theoretical results are compared with experimental data measured in model immersing experiments.

The self-imaging effect can be obtained as the result of the diffraction of a plane wave by the periodic structure. It is known as the Talbot effect. The self-imaging phenomenon is discussed here also from the new viewpoint as a class of the propagation-invariant wavefields. The repetition of an object can be achieved by the superposition of nondiffracting beams.

In this paper a high-power Nd-doped double-clad fiber laser is presented. From 20 m long fiber with laser core in 12 μm diameter (NA=0.12) and pump core in 400 μm diameter (D-shaped, NA=0.38) we obtained 10 W cw-output power. Nd-doping concentration has been at the level 1300 ppm and attenuation in the laser core has been less than 10 dB/km (for λ=1100 nm). High power diode laser module operating at λ= 808 nm has been used as a pump unit. This pump ensured 30 W cw output power. As a result we have built a coherent source of radiation generating 10 W cw output power with slope efficiency 63 per cent.

In laser scanning devices using a projection method of measurement a narrow laser beam moves parallel to itself. If the velocity of scanning of the plane of the object under control is constant then the duration of the video signal which is formed behind the object will correspond to the object’s size lengthwise the direction of scanning. If the object is not flat the duration of the video signal will not correspond to the size of the object due to the fact that in the process of its formation there takes part the beam reflected from the surface of the object under measuring. Thus the error appears in the result of measurement. The error which depends on the object’s configuration and reflectivity may be rather significant. The formula of calculation of the error as a function of the object’s surface curvature and height of microroughness of the surface is presented in the work. There is suggested the way of compensation of the error which consists of covering synchronously to the movement of the scanning beam and by turns the halves of the sensitive areas of the bielement photodetector located symmetrically to the optical axis.

Principles of automatic two-coordinate stand building are discussed. A base of using the stand is direct frequentative high-accuracy measurements of fixed angles for various zenith directions. Results of these measurements are introduced into special microprocessor for composing system of simultaneous error equations. The solution of the system makes it possible for setting both general instrumental errors of horizontal and vertical angular measurements and separate components of these errors. The system of base directions is set by two-coordinate photoelectric autocollimators aiming to special prism standard. The standard is certified beforehand and used then periodically for verification of the spatial stability of the stand. Analysis of an accuracy has illustrated that the error of certification may be not exceeded by 0,3 angular second for frequentative measurements if the error of the autocollimators are less to 0,1 angular second.

The contribution is to present both the theoretical and experimental analysis of a wedge prism, which allows us to perform very small angle deviation of a passing beam in a simply way. No high precise steering element is necessary. The results of the theoretical analysis, i.e. the dependence of the propagation vector on the angle of incidence had been verified experimentally, using both Mach-Zehnder interferometer and a holographic grating. The results obtained have proved the advantage of the method proposed, which may be of great importance anywhere if small-angle deviation of propagation wave vector is needed.

A CCD image sensor introduces noise to an image. This paper deal with main disturbing effects and their corrections. Statistical properties were computed from raw and corrected real CCD images. Some types of noise is possible to reduce by sensor cooling and image processing.

The main problem for CMOS active pixel sensors (APS) design is its fill factor and photosensitivity improvement. Using developed CMOS APS models we have solved this problem as mathematical optimization task. The fill factor is the aim function. The limits are: time delays, signal-to-noise ratio, horizontal and vertical MTFs, pixel sizes, and project rules. The simulation results for APS based on 4 transistors are given.

A new white-light spectral-domain interferometric technique is used to measure the group velocity dispersion (GVD) in optical samples of known thicknesses. In the experimental setup comprising a halogen lamp, a Michelson interferometer with an optical sample, and a low-resolution spectrometer, the equalization wavelength as a function of the displacement of the interferometer mirror is measured by the spectrometer. From the measured equalization wavelengths either the differential group refractive index of the optical sample as a function of the equalization wavelength or the difference of the mirror displacements at two different equalization wavelengths is obtained to determine the GVD in the optical sample. The new white-light spectral-domain interferometric technique is applied to measure the GVD in two fused-silica optical samples of known thicknesses. In a broad spectral range it is confirmed that the GVD in both samples agrees well with the GVD resulting from the Sellmeier dispersion equation.

We consider the output of a longitudinally pumped heavily doped Er:Yb:phosphate glass laser. We experimentally observe that the characteristic curve output-versus-input is not linear and exhibits bistability. A theoretical approach, based on a thermal lensing effect that is different depending on whether the laser is ON or OFF and on the overlapping mismatch between the pump and the laser spot sizes, provides an excellent description of the experimental results.

A new class of structures based on fibre Bragg gratings enable the next generation of lightwave communication systems. However, these devices require precise recording and determination of the fibre Bragg gratings characteristics for optimized performance. In this paper we present a technique for a precise spatial characterization of gratings based structures. A theoretical model as well as the corresponding experimental setup are presented and compared.

Non-destructive 3-dimensional images of the effect of refractive index change within a fiber Bragg grating have been recorded using the differential interference contrast imaging technique. The refractive index change indicated by the images is highly non-uniform.

In this contribution we compare the thermal stability of type I and type IIa gratings written in germanosilicate fibers. We study and compare their central wavelengths drifts and variations of the maximum reflectivity with temperature. Also, two other important factors, the bandwidth and group delay characteristics are characterized, compared, and the differences justified, based on the gratings physical structure.

The Finite Difference Time Domain Technique is at present the most widely used tool employed in the study of light propagation in various photonic waveguide structure. In this paper we derived an explicit finite-difference time-domain (FDTD) method for solving the wave equation in a four optical waveguiding rectangular structure. We derive the stability condition to achieve the stability in nonlinear media region, we also check that the wave equation used is consistence and convergent with the approximate finite difference equation. Our method is tested against some previous problems and we find a high degree of accuracy, moreover it is easy for programming. Numerical results are illustrated for a rectangular waveguide with four layers, where one of these layers is a nonlinear medium.

As the use of opto-microwave systems having microwave modulation bandwidth is increasing, the efficient measurement of opto-electronic S-parameters will be very useful to their overall design and characterization. A new generation of tools is required for the measurement of fundamentals parameters such as the microwave frequency response, bandwidth, gain and return loss of microwave photonic components. Current lightwave measurement techniques are primitive when compared with conventional RF and microwave network analysis. A solution for accurate measurements is a system based on the development of an automated bilateral calibration which could be implemented into a millimeter network analyzer (modulation frequency exceeding 20GHz) in order to fully characterize some optical and opto-electronic components. This lightwave network analysis is based on the microwave modulation response of optical components and optical fibres as lines of transmission, which require technologically compatible standards of calibration, along with an extended definition of S-parameters.

This article deals with evaluation of subjective and objective image quality. Another way how to assess an image quality is based on human vision models. Special model of the human visual system has been designed, tuned, tested. Its suitability for the image quality assessment has been evaluated using compressed images and by comparison of modeling results with standard subjective quality test results.

Far-Field non-gaussian fundamental transverse modes have been obtained in CW end-pumped Nd:YVO₄ microchip laser for particular cavity lengths. Such profiles appear at threshold and are not distorted when pump power increases but they strongly depend on the pump to mode size ratio. An implemented theoretical model qualitatively reproduces these transverse profiles. It is based on the hypothesis of diffraction effects of the resonant intra-cavity field on a Gaussian gain profile. Dependence of the pump to mode size ratio on such profiles will be also theoretically explained.

Dicke superradiance mechanism is suggested as a transition phase from spontaneous to stimulated emission in semiconductor laser heterostructures. Model, which describes “macrodipoles” formation in the active layer of heterostructures is proposed. Estimated characteristic radiation time of these “microdipoles” was obtained in sup-picosecond range, which is in a good agreement with our previous experimental results.

Bragg gratings written in high birefringence (HiBi) fibre optics can be used as sensors for multiple parameters, such as stress along different axis and temperature. Their use as sensors require the characterization of the HiBi fibres, because the specific fibre parameters can induce different responses to the sensor system. In this work we analyse, using finite elements methods, stress effects over three types of the HiBi fibres: Bow tie, PANDA and internal elliptical cladding. We also characterize the spectral response of gratings written in HiBi fibre as a function of the input states of the polarization. The obtained results are discussed.

The temperature dependence of propagation characteristics of periodic magneto-optical and dielectric multiplayer films made of alternating layers of these materials having a symmetric periodicity with the center of the structure under a magnetic field is analyzed. The magnetic induction on this type of materials is temperature dependent and modifies the transmission and reflection characteristics of these structures. The variation in the transmittance, reflectance or Faraday rotation in function of the temperature makes possible the use of this type of structures as a transducer element for magnetic field and current sensing.

An analytical mathematical model of the double heterojunction NpN bipolar phototransistor with abrupt heterojunctions in three terminal configuration is presented. The thermionic-filed emission and diffusion of injected carriers is considered and the Ebers-Moll type relations for the collector and emitter current are obtained. Several steady state characteristics of the phototransistor structure are calculated (optical gain, quantum efficiency, responsivity).

Materials with non-linear properties such as thermal hysteresis of birefringence, electrooptic, thermooptic, piezooptic and thermochromic phenomena are very interesting both from scientific and practical points of view. They can be applied to photonic technology as optical memories, optical modulators, temperature and stress sensors. The examples of such materials are A₂MX₄ and AMX₃ crystals (where A organic cation, M transition metal, X halogens). Possibilities and limitation of the A₂MX₄ and AMX₃ crystals growth from water and organic solution have been discussed in order to determine the optimal parameters of the growth.

To have a complex view on giant pulse generation, a more precise computer model of the build up Q-switch pulse in solid-state laser was realized. As a time starting point of the rate equation calculation, the moment of a flashlamp trigger was chosen. A system of three or four main differential rate equations describes the energy transfer from a pumping source - capacitor to an output giant pulse. Two laser active media, i.e. ruby and alexandrite, were examined with this model. A passive Q-switch ruby laser needs solving of the system of four differential equations; three differential equations gave the computer results for electro-optically Q-switched alexandrite laser.

Properties of optical beams are subject of systematic research. The particular attention is focused to the coherent and noncoherent light beams characterized by the degree of spatial coherence µ=1 and µ=0, respectively. Realization of the source with the controllable degree of spatial coherence provides a possibility to examine the light properties during propagation with 0<µ<1. The light provided by that source was applied to the generation of various types of the pseudo-nondiffracting beams.

We report on the different regimes observed in a bipolarized neodymium-doped fiber laser self Q-switched by a thin slice of a polymer-based saturable absorber. We demonstrate the interplay between the total losses and the loss anisotropy induced respectively by defocusing the saturable absorber and by tilting the cavity mirror. Starting from a global chaotic behavior for low-losses (i.e. good cavity) configuration, the system evolves toward n-periodic (n= 4,2 and 1) regime for increasing losses (bad cavity configuration). Stabilization of the regimes depends on the anisotropic losses introduced. These regimes have been identified as to be due to non-linear coupling through saturable absorber between two distinct polarized modes. These modes have been experimentally resolved. Simple model based on a bipolarized fiber laser reproduces such dynamics.

Optical properties of Er:YAG and Er:YAP materials and layers were studied. Layers were grown by KrF laser ablation (248 nm, 20 ns) from Er-doped targets. Composition, crystallinity, luminescence and results of spectroscopic ellipsometry are discussed. Films were mostly amorphous for substrate temperatures up to ~ 975 °C. Luminescence corresponding to Er⁺³ ions was observed on all samples. Waveguiding properties were estimated.

Linear electro-optic coefficients r₁₃ and r₃₃ of LiNbO₃ crystal were measured in the setup of Mach-Zehnder interferometer with He-Ne laser. Sample was placed in closed circuit He cryostat, so temperature dependency was investigated from 150K to 330K. Electro-optical coefficients r₃₃ and r₁₃ were constant in this temperature range. In the measured frequency range 200 Hz-10 kHz, there is no change of the E-O coefficients with frequency.

Protection represents fundamental point in designing transport network, which, at the same time, is one of the basic reasons for the development of SDH technology. Protection mechanisms in SDH technology maximally meet the network “service survival in failure conditions”. The backbone of the future transport network will be WDM technology, which also meets this requirement. Protection mechanisms in SDH technology, as well as reasons for WDM technology introduction are topics of analysis made in this paper, together with protection mechanisms in WDM technology and protection strategy in combined SDH-WDM technology. Last chapter of this paper also represents a suggestion for introduction of WDM technology in existing HPT Mostar’s SDH network.

The mathematical models of dispersive optical bistability in unidirectional ring cavity yield the transmitted intensity I_t as a function of the input intensity I_in with additional parameters (mirror reflectivity R and phase shift β). There are two feedback elements in this description: the energy (and, hence, also causal) feedback quantified by R and the purely causal feedback given by dependence of the phase shift on the transmitted power, β=β₀+β₂I_t. The apparatus of causal diagrams method is used to represent and analyze phenomena in the ring cavity. The region of physically unstable states is marked by the condition t_loop>1, where t_loop is the transmission function of the feedback loop I_tβI_inI_t present in the diagram. Besides the critical points defined by t_loop=1 (which are linked to the existence of bistability), there are two conditions marked by t_loop=0 in which the cavity state is insensitive to the values of R.

We examine the revival of the nondiffracting vortex beam after its interaction with the 2D obstacle. We verify that the intensity profile, the phase topology and the spatial distribution of the orbital angular momentum of the beam transmitted through the obstacle regenerate to the initial form during further free-space propagation. The healing effect appears even if the obstacle possesses the helical phase and the interaction is accompanied by the exchange of the orbital angular momentum. The effect is applicable to the design of the light powered micromechanical rotors.

The prism coupler allows the resonant excitation of leaky modes whose transverse field distribution in the guiding structure is close to that of guided waves. The paper is concentrated on the study of the influence of the associated electromagnetic resonances on the linear response of this distributed coupler while taking into account the width of coupling gap and the induced anisotropy of waveguiding media. The characteristics of prism coupling into anisotropic thin films are calculated by 4×4 matrix algebra.

Mode spectroscopy is a widely used technique for characterizing planar optical waveguides. Prism couplers are mostly used due to their versatility. For higher-index waveguides like SiO₂/SiN or GaInAsP/InP, prism coupling is hampered by the lack of suitable high-index material for fabricating coupling prisms. In this case, short-period grating couplers could be used, instead. We describe the fabrication of “exchangeable” grating couplers with 1200, 1800, and 2400 lines/mm into a photo-curable polymer by copying master grating generated holographically. The grating couplers were applied to glass and Si/SiO₂/SiN waveguides, and results were compared with those obtained using prism coupling. Fabrication of gratings with shorter periods is under way.

All-optical triode derived from tandem wavelength conversion was realized using a distributed feed back laser diode and a semiconductor optical amplifier. The first of the converter was based on cross-gain modulation in the DFB laser diode whereby conversion from an input wavelength of 1555 nm to the wavelength of 1548 nm was accomplished in the laser diode. The 1548 nm was converted to a wavelength of a control laser in the semiconductor optical amplifier in the second stage. The output wavelength was selected using a tunable control laser and an arrayed wavelength grating filter. The output power with the input signal was controlled by the control power. The all-optical triode has the input and output characteristics in the same manner as the triode in electronics.

Integrated optics structures require a broad variability of the geometric and optic parameters of waveguides. This work presents an option for low-loss glass optical waveguide preparation, with a wide range of geometrical and optical properties, using relatively inexpensive substrates. Ion exchange method was used for the creation of those waveguides. Extension of waveguide characteristics was achieved using 1) different types of substitution ions (particularly K⁺, Ag⁺ and Li⁺), b) electric field-assisted ion exchange, c) different types of glass substrates. The results are readily applicable to the development of new optoelectronic structures because the technology also supports the design of very complex topologies.

The influence of the temperature changes in surroundings on the field distribution of the optical fiber above the critical value of the normalized frequency will be shown in contribution. The contemporary influence of the temperature changes and fiber bending will be viewed together with a discussion if it could be possible to separate these particular components. Conditions, which are necessary to be satisfied, will be shown as well. The numerical solution will be made for standard telecommunication fiber and for wavelength when the optical fiber supports the limited spectrum.

In this paper we report some original results concerning the evaluation of some parameters which characterize the Er³⁺-doped LiNbO₂ M-mode straight waveguide amplifiers pumped near 1484 nm. The derivation of the spectral optical gain, the Fano Factor and the statistical fluctuation which characterize the photon statistics are performed in the small gain approximation and the unsaturated regime by using erfc, Gaussian and constant profile of the Er³⁺ ions in LiNbO₃ crystal. The simulation results show the evolution of the above mentioned parameters under various pump regimes and waveguide lengths and can be used for the design of the integrated optical devices.

A general matrix method for description of light reflection and transmission in systems containing of thin and thick anisotropic layers is proposed. The method is based on matrix summation of partial waves. The non-coherent summation of intensities in a thick layer is characterized using the coherence vector formalism. The measured quantities (magneto-optical rotation and ellipicity), or Mueller matrix components are obtained from 4×4 matrix describing transformation between coherence vectors, hereafter the coherence transforming matrix. In the case of polar geometry, the base consists of right and left-handed circular polarizations and the matrices have diagonal form.

Study of fabrication and properties of the carbon layers by using the PACVD (Plasma Assisted Chemical Vapor Deposition) apparatus is reported. The layers were grown on silicon substrates with methane as the precursor and were then doped with the erbium ions by treating the fabricated samples in glycerin or in the solution of erbium nitrate. To obtain deeper erbium containing carbon layers (up to 1 μm) the “sandwich method” was used based on repetition (three times) of carbon deposition and subsequent diffusion of erbium after which followed annealing in vacuum oven. The obtained results proved that it is in principle possible to fabricate the erbium containing carbon thin optical layers.

Web cameras are widely used as an image acquisition systems that are cheap, available and easily configured. Their settings are implemented electronically and the software drivers have a limited access to the internal characteristic of the cameras. These settings are prepared to cover the most common of the illumination conditions and scenes. The images provided by these cameras not only have to do with the physical characteristics of the detector array, but also with the compression algorithm used to present the images onto a display. In this contribution we apply the principal component analysis to a set of frames obtained by web cameras. This method allows to extract different spatial-temporal patterns of the noise of the cameras.

The noise characterization of a set of frames can be treated by means of the principal component analysis. The main advantage of this method is that it provides a set of eigenimages that can be grouped into processes. These processes may be identified with actual sources of noise. In this scheme, bad pixels are extracted as those pixels showing an anomalous behaviour. The principal component analysis also allows to extract information about the character of the temporal evolution of the signal of the pixels. The bad pixels are identified by evaluating their place in the distribution of signal of the whole data set.

Packaging and testing represent a good fraction of the cost of the current photonics devices. Packaging includes the complex transition from the input/output fibers to the device itself, which requires very accurate alignment, bonding, tracking while the curing process takes place, and verification of the complete assembly characteristics. Industry needs to lower the cost/increase the production rates of these devices and the answer to these needs is to automate assembly and testing. The most efficient way of achieving this is by tightly integrating image processing and analysis techniques with nanopositioning motion systems and data acquisition. The paper will provide details, results and performances of alignment systems based on these techniques.

For the last decade sensor architectures with embedded fibers found their application in large structure monitoring and proved their capability to replace existing techniques for monitoring of linear strain, temporary or permanent none-uniform strain and load, temperature, vibrations, bending, or complex strain-temperature, vibrations-temperature influences, etc. Such sensor architectures, called smart structures, use different sensing mechanisms, in one of which - fiber Bragg grating (FBG) - is applied as a sensitive element. Because of high sensitivity, absolute measurement ability, possibility to work reliable in adverse environment, such as electromagnetic fields, radiation, extreme temperature, and quick response time, FBGs are object of numerous research of leading laboratories worldwide. Some problems are still remaining in this field, although there have been some ways found to solve part of them. This paper discusses some aspects of different fixing mechanisms of FBG and provides evaluation and comparison of methods of FBG integration in sensor housing or in sensor architecture.

Bleaching relaxation in PbS-quantum-dots-doped phosphate glasses in dependence on the dot size is presented. The fast bleaching decay component is increased from 14 to 93 ps as the dot size increased from 4.7 to 5.8 nm. The glasses are employed as saturable absorbers for mode-locking and Q-switching of 1.3 µm neodymium lasers. Q-switched pulses of 120 ns (0.1 µJ) in duration (energy) and the average output power of 3 mW from diode-pumped Nd³⁺:KGW laser and ultrashort pulses of maximum 250 µJ in energy and 150 ps in duration from a Nd³⁺:YAP laser were obtained.

We demonstrate the application of a twin-core fiber comb filter to the generation of high repetition rate pulse trains in fiber lasers. We have found experimentally that passive mode locking of the fiber laser can be established due to concurrent effects of a nearly periodic transmission function of the twin-core fiber filter and of the modulational instability. The period of the generated pulse train is determined by the intermodal dispersion of the twin-core fiber inserted into the fiber laser cavity. A repetition rate as high as 206 GHz was achieved. The width of the generated pulses was 2.7 ps.

Photonic crystal fibres having a microstructured air-silica cross section offer new optical properties compared to conventional fibres. These include novel guiding mechanisms, new group velocity dispersion properties and new non-linear possibilities.

We present a new method to calculate the scattering of light at the surface of a photonic crystal. The problem is solved in terms of virtual surface-current distributions and the calculation takes full advantage of the existing infinite-space plane-wave expansion method for obtaining the photonic band structure. Working with surface currents makes the calculations less-time consuming by means of reduction of the dimensionality in the problem. The method is tested and illustrated for semi-infinite two-dimensional photonic crystals of small and large dielectric contrast.

It is shown that small metallic inclusions can have a dramatic effect on the photonic band structure of diamond and zinc blende structures. In the case of silica spheres with a silver core, the complete photonic band gap (CPBG) between the 2nd-3rd bands opens for a metal volume fraction f_m≈ 1% and has a width of 5% for f_m≈ 2.5%. Absorption in the CPBG of 5% remains very small (≤ 2.6% for λ ≥ 750 nm). These findings open the door for any semiconductor and polymer material to be used as a genuine photonic crystal building block and significantly increase the possibilities for experimentalists to realize a sizeable and robust CPBG in the near-infrared and in the visible.

The optical response of a thick slab of a two-dimensional photonic crystal, obtained by taking a rectangular dielectric grating as the elementary building block, is computed and compared with the dispersion curve of the bulk. The role of the bulk and the surface waves of the system on the optical transmittivity is discussed. The “mirror effect”, computed by two of the present authors in self-sustained rectangular dielectric gratings, due to the interplay among traveling, evanescent and guided waves, is recovered and it seems to endure also in the semi-infinite photonic crystal.

We present in this work the optical properties of Er³⁺ ions in KY₃F₁₀ single crystals. After crystal growth and Xray diffraction analysis, optical absorption and emission spectra are recorded at low temperature (8 K). The Stark sublevel diagram is determined. The fluorescence decays of the main emitting levels have been measured and compared with those obtained in literature for other known laser materials.

Dispersion curve calculations for photonic opals and inverse opals have been performed with the aim of study the influence of the dielectric contrast and of the size of the spheres on the widths of the photonic band gaps. Disorder effects in this kind of system have been briefly discussed. Moreover, structural-defects and punctual-defects, which generate photonic states inside the photonic band gap have been studied by using Large Unit Cells approach.

No abstract available.

An important ingredient in improving Multi Photon Laser Scanning Microscopy, MPLSM, is the development of efficient two-photon fluorescent (TPF) probes. We previously reported on a new class of TPF probes, specifically designed in order to maximize their efficiency in potential MPLSM applications. The fluorophores are based on a tetraketo derivative (TK) with a symmetric structure Donor-Acceptor-Donor (D-A-D). Those fluorophores have the following properties: a) Very large two-photon absorption coefficients (δ ~ 1000GM); b) Two-photon excitation (TPE) peak wavelength strongly shifted to the red (λ ~ 1µm); c) High fluorescence quantum efficiency; d) Large Stokes shifts of the fluorescence bands. We extended our work to a new fluorophore from this class that is more suitable for biological settings. This new fluorophore has a structure of crown-TK-crown that incorporates the ability to trap metal ions such as calcium. The TPE wavelength dependence of the TK-crown derivative is very similar to its analogous linear derivative with enhancement in the value of the cross-section, due to the stronger donor moieties. The TPE cross-section for the TK-crown derivative was about δ = 950 GM at λ_max = 980 nm.

This paper reports on Organic Light Emitting Diodes (OLED) the structure of which has been inverted in order to have a light emission through the top electrode instead of through the substrate. This technology is of prime importance for high resolution active matrix displays and microdisplays as well. The key point of such a procedure is the deposition of the Indium Tin Oxide (ITO) transparent top anode. This was carried out onto the organic films structure by RF sputtering under soft enough conditions so as to avoid as much as possible any deterioration of the underlying organic layers (room temperature deposition, low plasma power density and minimal bombardment effect). The electrical and optical properties of ITO as a function of the deposition conditions are first described. Hall effect measurements show that ITO films can be grown at room temperature with a high mobility (40 cm²/V.s) and a carrier density exceeding 5 10²⁰ cm^-3. The surface roughness as a function of the plasma conditions was determined by the AFM and can be as low as 12 Angstrom. The non invasiveness of the proposed ITO deposition conditions on organic layers was assessed by measuring the photoluminescence (PL) degradation of (8-(hydroquinoline) Aluminum (Alq₃). It was shown that under optimized deposition conditions, no appreciable PL degradation of the organic layers was observed. At last hole only Silicon/Al/Poly(N-vinylcarbazole)(PVK)/Poly(3,4)ethylenedioxythiophene / Polystyrenesulphonate (PEDT/PSS). ITO diodes and Silicon/Al/Alq₃/NPB/CuPc/ITO diodes were processed, characterized and compared to standard “through the substrate” emitting diodes.

We present the promising single- and multi-pass properties of a very simple Diffractive Optical Element which is a phase aperture. The latter is a two-level transparent phase-plate with a phase discontinuity of magnitude π. In the single-pass case the phase aperture can be used for laser beam tailoring. It is able to convert a Gaussian beam into a super-Gaussian, a ring-shaped or a doughnut profile, and an elliptic into a circular beam. In the multi-pass case the phase aperture is inserted inside an optical laser cavity in order to enhance some of its properties: transverse mode discrimination and fundamental mode volume.

In this paper we discuss our approach to based on holographic techniques implementation of neuro-fuzzy predictor for processes, described by Fractal Brownian Motion (FBM) model. We use the model of the predictor as a Riemann - Stieltjes integral over the observed traffic of specific weight function. We discuss two-layered bi-directional optical neural network to find our solution. To find the weight function we use non-linearity in the correlation layer of the neural network. In our experiments we used air-photograph of forest as this kind of images demonstrates self-similarity property and can be described by the FBM model. As a first step we used approximate solution for the weight function, achieved by using binary filtering function in the correlation layer. We demonstrate experimental results and discuss directions of our future investigations.

Low-cost adaptive optics is applied in lasers, scientific instrumentation, ultrafast sciences and ophthalmology. These applications demand the deformable mirrors to be simple, inexpensive, reliable and efficient. We report on a novel type of ultra-low-cost deformable mirror with thermal actuators. The device has response time of ~5 s, actuator stroke of about 6 μm, temporal stability of about λ/10 rms in the visible range and can be used for correction of rather large aberrations with slow changing amplitude.

In the present work consideration is given to theoretical and experimental analysis of the possibilities for improving the efficiency of multiwave mixing in the process of dynamic hologram recording in solutions of complex organic compounds with additional irradiation of resonant medium at a frequency falling within the absorption band from the excited level. Three- and seven-fold increase in the diffraction efficiency has been realized in Rhodamine 6G dye for four- and six-wave missing, respectively.

Holographic diffractive doublets are optional systems for collimation of highly elliptical light beams, which are emitted from edge of diode-lasers. The first element converts an impinging astigmatic divergent beam into a cylindrical divergent beam, and the second element transforms the cylindrical beam into a collimated beam. In contrast to previous concept of the doublet with perpendicular input and output, another non-parallel scheme is considered, with the cylindrical wave front from the first element perpendicularly impinging upon the second element. A strongly off-axis holographic set-up is used for recording of diffractive elements in photoresists layers deposited on glass substrates.

We present a novel technology for spatial light modulators based on electrostatic deformation of viscoelastic layers. To fabricate the modulator structure, we bond two silicon chips using an intermediate viscoelastic layer and then etch away the top chip. This results in a very high optical quality viscoelastic layer deposited directly on top of the bottom chip. Light modulation is achieved by deforming the deposited viscoelastic layer using electrodes integrated into the bottom chip. Before bonding, the top chip is coated with a 80nm layer of aluminum and 50nm layer of nitride, that serves as the etch stop and reflector at the silicon. The thin nitride layer functions as the etch stop. Special technology was developed for low-stress side and back etch protection of contact pads of the devices. The continuous reflective membrane results in a 100% optical fill factor, enabling the modulator to handle relatively high optical loads. Also, given a sufficient bias voltage, the voltages on the electrodes should be in the range of 15-30V, making integrated solutions possible. Applications lie in the field of optical communication networks and projection displays.

In this paper, we show a design example based on a couple of holographic gratings allowing the injection and the extraction of infrared light from a wave-guide. By means of suitable register conditions at 633 nm, we obtain a wave-guide when reconstructing in the infrared. In this way, we avoid the use of auxiliary tools, like a prism and index matching liquid, during the register process. We present some experimental results obtained under reconstruction beams at 980 nm.

We describe a long-wavelength Mach-Zehnder interferometer for digital off-axis Fresnel holography with a pyro-electric detector array used to record digital holograms of an extended object at 10.6 μm. We show that, although the spatial resolution of the pyro-electric detector array is much less than that of typical CCD cameras working in the visible region, good reconstruction of the amplitude and phase of the object wavefield can be obtained. The principle of Fresnel reconstruction in digital holography is described and results of reconstruction process for object size of the order of 700 μm are presented and discussed.

Techniques for encoding composite diffractive optical elements (DOEs) oriented to the use of spatial light modulators (SLM) are discussed. The use of the dynamic SLMs presupposes the real-time encoding. It turns out to be effective to use the composite DOEs, with their complex transmission function being derived as a superposition of Fourier (or Fresnel) images of the corresponding image segments (spots, line-segments). Composite DOEs to form desired images in different planes are considered. A modification to the fractional encoding technique where every pixel of the amplitude-phase function is encoded into a single phase function pixel is proposed.

This article deals with an application of the broad-source image plane holography, which offers nonscanning confocal imaging, i.e., real time imaging. We have developed a laboratory version of a holographic confocal microscope (HCM). By the measurement of the axial intensity response for a perfect plane mirror we have verified the confocal imaging capability with the depth discrimination. The noncontact surface profiling possibility was verified by processing series of optical sections with consequent 3D reconstruction of the real surface profile.

A basic description of the system for optical tomography with diffusive illumination of the phase object is presented. The configuration of the system allows automatic projection scanning of the studied phase object (such as a burner flame or temperature fields around heated elements) in the range of viewing angles from 0 deg to 90 deg. The object’s projections are obtained using multidirectional holographic interferometry and consequently digitized by a CCD camera. A computer then calculates the wavefront deformation for each projection, and the subsequent tomographic reconstruction of each horizontal slice of the object is processed. Finally, all slices are interpolated and displayed. Here we present the experimental setup along with some experimental results.

The Quaternion theory is applied to a Semimagnetic Semiconductor Microcavity, a Fabry-Perot cavity in which a Quantum Well has been placed in its center. The Optical Scattering Matrix calculus and the Mason’s rule are applied to characterize the device, and with the employment of the Pauli decomposition, the different phenomena, like linear and circular birefringence and dichroism, are measured. This analysis is developed for different configurations of the microcavity under the influence of an external magnetic field, which produces very important changes in the polarization properties of the light propagating into the microcavity.

The Raman gain coefficient in G.652 (standard single mode) optical fibres is measured, based on the power transfer between a high intensity pump signal and on a counter-propagated broadband probe signal technique, complemented with spontaneous Raman spectroscopy. The Raman gain coefficient measured over a 90 nm wavelength range yield to a Raman gain slope and to a maximum value of the gain coefficient of 7.482 10^-27 mW^-1 Hz^-1 and 0.540 10^-27 m W^-1, respectively. The values of 3.03 fs, 12.40 fs, 40.78 fs and 0.18 are experimentally obtained for the Raman time constant, first and second parameters of the Raman response function and fractional contribution of the delayed Raman response, respectively. These values are in agreement with previously reports and consistent with the obtained simulation results.

We investigated the optical properties of Er³⁺ ions in LiNbO₃ planar waveguides produced by annealed proton exchange (APE) using the site-selective method of combined excitation-emission spectroscopy at low temperature. The spectroscopic results obtained for the luminescence in the green spectral region (≈ 550nm) under the direct laser excitation at 450 nm and under two step laser excitation at 980 nm (up-conversion process) are compared with bulk material and LiNbO₃ waveguides produced by Ti-diffusion. Notable differences have been found in the kind of defect sites, in their number distribution, and in the inhomogeneous broadening of the optical transitions.

We study theoretically the nonlinear frequency characteristics of the transverse magnetic surface waves on the interface of an antiferromagnet and superconductor structure. The complex wave number of TM wave is computed by solving the dispersion equation in order to find out the effect of the temperature of superconductor on the reduced phase and attenuation constants. Both effects of the nonlinearity and the temperature of superconductor have been studied on the power flow as a function of the reduced phase and attenuation constants.

We investigated the IM-IM and IM-PM coupling (conversion) coefficients of a microwave modulated optical link, where a Bragg grating is inserted. The Bragg reflector allows measurements accessing only to one fibre ends, and simultaneously increases the transmission length. Numerical simulations of the IM-IM and IM-PM coupling coefficients are realized as a function of the modulation frequency, fibre length and laser power, using the method derived by Ramos and Marti. The experimental measurements deviated considerably from the theoretical expressions, particularly at low powers (< 10mW). We expect the method to be useful to measure non-linear and dispersive characteristics of installed fibre links.

We present a study of the annealed proton exchanged waveguides fabricated in erbium and in a mixture of erbium and ytterbium (RE) bulk doped lithium niobate. Waveguiding properties and composition of the RE doped waveguides were not substantially changed compared with those fabricated in pristine lithium niobate. However, presence of the doping ions decreases the r₃₃, but a carefully designed APE technology can increase the r₃₃ almost to the value of the pristine LiNbO₃. According to our results the proton exchange need not necessarily change the efficiency of the 1,5 μm emission and certainly does not lower the concentrations of the RE.

The dynamics of orthogonal polarization modes in anisotropic plane resonators with resonant medium has been studied. A model of light-induced anisotropic effects in a resonant medium under polarized excitation in conditions of strong saturation has been developed. The origination conditions of polarization instability and its influence on spatial-temporal dynamics have been determined. The methods of arranging the laser beams with special polarization structure have been suggested.

We consider an Yb-doped double-clad fiber laser in a unidirectional ring cavity containing a polarizer placed between two half-wave plates. Depending on the orientation of the phase plates, the laser operates in continuous, Q-switch, mode-lock or unstable self-pulsing regime. An experimental study of the stability of the mode locking regime is realized versus the orientation of the half-wave plates. A model for the stability of self-mode locking and cw operation is developed. The model is reduced to a master equation in which the coefficients are explicitly dependent on the orientation angles of the phase plates.

No abstract available.

We took into account the generation of high-order Stokes and anti-Stokes components in our method of anti-Stokes generation at stimulated Raman scattering in a medium exhibiting variations of the third-order nonlinearity along the direction of propagation. The dependence of Raman gain dispersion on quasi-phase matching conditions was studied by numerical simulation. The possibility of effective periodical quasi-phase matching structure realization for hydrogen was determined. We received the multiwave models of media in which the efficiency of first anti-Stokes generation reached ~40%. The results of our research can be used for creation of new effective nonlinear-optical frequency converters and Raman amplifiers.

In this contribution the routing capabilities of time/wavelength codes in Optical Code Division Multiple access are observed by means of the study of two devices for achieving the wavelength part code conversion. Multi-wavelength conversion will be achieved by using a Semiconductor Optical Amplifier and a Reflective Semiconductor Optical Amplifier. The conversion results for the two devices will be characterized and compared in terms of applicability to the conversion in hands and to the referred application.

Potentially low loss lithium ion-exchanged glass waveguides were fabricated in various types of silicate glass substrates and characterized by a number of analytical as well as optical methods. The migration of lithium ions was studied in details using the NDP method. The small radius of the Li⁺ and its high mobility resulted in high strain in the exchanged region causing thus heavily surface damage of the samples. Two crucial points of the matter were solved: to avoid the surface damage the fabrication temperatures must be above the transformation point of used glass (Tg), and to fabricate few-modes waveguides the highly Li-diluted reaction melts must be used.

All-solid-state diode-pumped intracavity Raman laser was realized. The laser was based on three-mirror linear cavity with triangular Brewster-angle-cut Nd:YAG slab crystal pumped by 300 W quasi CW diode Q-switched by Cr⁴⁺:YAG saturable absorber operated at 1064 nm. The BaWO₄ crystal (6×6×33 mm) was used as a Raman converter. After the Raman laser optimization for the first Stokes (1180 nm) the reproducible conversion efficiency was about 40%. The corresponding output energy and pulse duration were 1.46 mJ and 3.5 ns, respectively. The highest Raman laser output energy was reached 2.3 mJ (efficiency 55%). The second and third Stokes with first anti-Stokes lines were also detected at the laser output.

Medium temperature (350 °C) localized doping of Er³⁺ was studied in lithium niobate (LN) and sapphire single crystal wafers that were cut in various crystallographic directions. It was found that the efficiency of the doping was connected with orientations of the substrate wafers of both LN and sapphire, and with the presence of mobile lithium ions in the structure of LN. The basic interstitial mechanism of erbium incorporation into the structure of sapphire and LN is in the latter accompanied with erbium for lithium ion exchange. While the rate of the interstitial diffusion was higher in the wafers oriented perpendicularly towards the cleavage planes of the crystals, ion exchange process was significant in the wafers cut in cleavage planes. Waveguiding properties in erbium doped lithium niobate originated rather from presence of erbium in the structure of the crystals than being a consequence of a weak proton exchange. Luminescence properties of the fabricated samples are also presented.

We report a new interferometric technique for measuring the ordinary and extraordinary refractive indices of uniaxial crystals. The technique is based on the measurement of the rotation-dependent phase changes of the optical path length in crystal plates. Accurate measurement of the phase shift as a function of the rotation of the sample is achieved by using a fast-Fourier-transform based fringe analysis method for phase retrieval. The principle of the method is discussed and measurements of the ordinary and extraordinary refractive indices of a lithium niobate crystal are reported.

On the base of linear stability analysis of coupled-modes equations the conditions for complex spatial structures formation (symmetrical and asymmetrical, large- and small-scale localized states) have been determined. The possibility of the development of new all-optical elements for flip-flop operations based on coherent interaction of cavity solitons in conditions of symmetry-breaking instability is discussed.

Two-photon absorption of 1.55 μm light in quantum well InGaAsP/InP laser heterostructures has been measured. Nonlinear response as high as 0.78 nA/mW² has been found. Minimal detectable peak power 60 μW allows using this kind of semiconductor waveguide as a detector in optical autocorrelator to investigate low-power signal.

We present a study of fabrication and properties of planar optical waveguides fabricated by Ag⁺, Cu⁺, Cu²⁺ and Er³⁺ ion exchange in a variety of commercial as well as non-commercial optical glasses. The properties of the waveguides are discussed from the point of view of composition of the substrate glasses (taking into account the ratios of the bridging and non-bridging oxygen atoms in the glass matrixes and fining agents), luminescence and waveguiding properties as refractive index profiles and birefringence. The samples containing exclusively Cu⁺ exhibited very strong blue-green luminescence despite their low content of copper. The localized Er³⁺ doping into the glass wafers is presented for the first time.

It has been considered the transformation efficiency of laser radiation into cylindrical surface plasmon-polaritons on a resonance harmonic grating covered cylindrical waveguide. It has been investigated in detail the case when polaritons propagate along a waveguide. The results are interesting for the development of effective probes for near-field optical devices.

It is studied theoretically and experimentally how a wave reflected from the surface influences the distance of the trapped sphere from the beam waist. The reflected wave interferes with the incident one and they create a standing wave component in the final axial intensity distribution. This component modulates the trapping potential and creates several equilibrium positions for the trapped sphere. When the beam waist approaches the surface, the potential profiles changes and causes jumps of the trapped objects to deeper potential well. We proved that these unwanted jumps of the trapped objects between the neighboring equilibrium positions can be eliminated by proper size of the sphere.

In this article we describe a combined system that uses optical tweezers to bring two living cells into contact and optical scalpel to punctuate their membranes at the contact point. This process initiates a fusion of both cells into one hybrid cell containing two nuclei. If the fusion product is viable, these nuclei tend to mix together. The spatial distribution of the nuclear material in the resulting hybrid nucleus is studied by analysis of positions of FISH (fluorescent hybridization in situ) signals of specific genetic loci in automated fluorescence microscope (high resolution cytometer). The obtained results are compared to the signals distribution of FISH in the original cells.

Photocurrent (PC) spectroscopic techniques have demonstrated to be helpful experimental method to investigate the local properties of bulk semiconductors, microstructures, surfaces and interfaces. We have measured locally induced PC of semiconductor quantum structures using a technique of reflection Scanning Near-field Optical Microscope (r-SNOM) in combination with Ti:Sapphire laser and tuning dye laser and with He-Ne laser. The r-SNOM employs an uncoated and/or Au-metalized single-mode fiber tip both in illumination and collection mode. Taking opportunity of the high lateral resolution of the microscope and combining it with fast micro-PL, it is possible to locate e.g. defects in a multiple quantum well grown by molecular beam epitaxy. Near-field characteristics of measured quantities are also discussed.

Submicron spatial resolution photoluminescence is used to assess radiative efficiency and spatial uniformity of GaAlAs/GaAs heterojunctions. Room temperature photo-luminescence of multiple GaAlAs wells with GaAs barriers was measured as a function of a facet of device perpendicular to the layer structure. The scanning near-field optical microscope is applied for the diagnostics of the defects in semiconductor devices for instance in a multiple quantum well grown by molecular beam epitaxy. Our high resolution studies reveal that the radiative recombination for the GaAlAs quantum well is approx. 50 times more efficient than for the underlying GaAs film. The comparison of the Far-field and Near-field characteristics of measured quantities are also given.

A new software package, suitable for performing polarization analysis in optical networks is presented. The user can input any initial state of polarization using Jones and Stokes vectors, the polarization ellipse and the density matrix. Each device and optical network can be defined using Jones and Muller matrices, and the quaternions, which represents the device in terms of the four Pauli matrices. The final state of polarization is calculated, and presented using the methods mentioned above, as well as the graphical representation of the polarization ellipse and the Poincare sphere. The extension to first-order component defects in general ellipsometry is included. It can be used for educational and research purposes.

Photonics as other multidisciplinary fields needs a special educational approach. Our teaching innovation is based on the assumption that training the skill to solve problems in an independent way with the use of computer-assisted learning deepens the understanding of the subject. The advantages of such approach consist in the focus on significant aspects and the ability to rely on previously and newly acquired knowledge of different fields. In addition, students have the chance to practise technical presentation design with multimedia tools. Some examples of multimedia web techniques applications to the presentation of selected topics in Photonics education will be described.

In the paper we present a new method for testing objectives for CCD camera. The method is based on determination of the modulation transfer function. The results were verified by experiments performed at the specially designed automated testing. The method, accompanying program software and hardware are applied in the teaching process of photonics at Institute of Micromechanics and Photonics, Warsaw University of Technology.

The submitted paper is describes a relevant experience in an introduction of photonic information processing techniques into the curricula of MSc course subject Image Processing and Photonics and PhD course subject Selected Parts from Photonics. The photonic information processing systems offer extensive computational power because of several advantages: the information carrier - photon - is the fastest one, massively parallel access and computation, some mathematical operations performed by physical effects (2D convolution, 2D Fourier transform).

Diffraction efficiency of surface-relief gratings with various shallow profiles is discussed. A general relation for the diffraction efficiency is derived under the assumption of Fraunhofer diffraction. The general relation is applied to several profiles mostly needed in practice. It is pointed out that shallow profiles can provide high diffraction efficiencies.

The test system for basic optical and electro-optical subjects checking has been worked out at the Optical Faculty, the Moscow State University of Geodesy and Cartography. The system has been divided up into intrasubject and intersubject groups. Examples of these tests are appeared.

A laboratory bench has been developed and a laboratory manual has been prepared for the practical course in optical data processing including the following laboratory exercises: “Spatial Filtering of Images”, “Optical Bistability”, “Intensity Self-Oscillations and Optical Chaos”, “Logic Optical Elements”. These laboratory exercises enable the students to study the analog and digital information conversion methods and the effects underlying them. The laboratory bench was created on the basis of the electrically controlled liquid-crystal elements and involved a computerized recording system for temporal and spatial characteristics of light beams.

For the first time the quasi normal mode treatment is used and extended to the description of the scalar field behaviour in one dimensional photonic crystals. A one-dimensional photonic crystal is a particular configuration of an open cavity, where discontinuities into refractive index give rise to field confinement. A discussion of the complex eigenvalues and eigenfrequencies, as well as the corresponding field distribution, is presented.