This PDF file contains the front matter associated with SPIE Proceedings Volume 9450 including the Title Page, Copyright information, Table of Contents, Introduction, and Conference Committee listing.

The Czech national R&D project HiLASE is a platform for development of advance high repetition rate, diode pump solid state lasers (DPSSL) systems with energies in the range from mJ to 10J and repetition rate from 10 Hz to 100 kHz. In this paper an overview and a status of the project will be given. Additionally some applications of these lasers in the hi-tech industry, which initiated their development, will be also presented.

This paper gives short overview of laser-based experiment OSQAR at CERN which is focused on search of axions and axion-like particles. The OSQAR experiment uses two experimental methods for axion search – measurement of the ultra-fine vacuum magnetic birefringence and a method based on the “Light shining through the wall” experiment. Because both experimental methods have reached its attainable limits of sensitivity we have focused on designing a vacuum laser resonator. The resonator will increase the number of convertible photons and their endurance time within the magnetic field. This paper presents an opto-mechanical design of a two component transportable vacuum laser resonator. Developed optical resonator mechanical design allows to be used as a 0.8 meter long prototype laser resonator for laboratory testing and after transportation and replacement of the mirrors it can be mounted on the LHC magnet in CERN to form a 20 meter long vacuum laser resonator.

Recently similariton (or self-similar pulse) fiber lasers have attracted great attention due to their capabilities of highenergy pulse generation that could find different applications in science and industry. Moreover it is very important to reach stable pulse generation for the application as a frequency divider in optical frequency standard. Hybrid modelocking mechanism was used for obtaining stable similariton generation at 38 MHz pulse repetition frequency. It involves two types of mode-locking mechanisms in the cavity - saturation of carbon nanostructures absorber (recovery time T_rt ~ 500 fs) and nonlinear polarization evolution based on the nonlinear Kerr-effect (T_rt ~ 10 fs). It was shown that total intracavity dispersion should be slightly positive for generating stable similaritons with duration of less than 90 fs and spectral bandwidth of more than 50 nm at 11.2 mW output average power that could be further applied in an all-fiber MOPA setup.

Fluoride-type crystals (CaF₂, SrF₂) doped with neodymium Nd³⁺ present interesting alternative as a laser active media for the diode-pumped mode-locked laser systems mainly because of their broad emission spectra as well as longer fluorescence lifetime in comparison with well-known materials as Nd:YAG or Nd:YVO₄. In comparison with Nd:glass active material, SrF₂ and CaF₂ have better thermal conductivity. In spite of the thermal conductivity decreases with doping concentration, these crystal might be interesting alternative for the Nd:glass mode-locked laser systems. In this contribution we present the first results of the Nd,Y:SrF2 mode-locked laser diode-pumped at 796nm. Mode-locking operation using SESAM was successfully achieved in the pulsed pumping regime (pulse-duration 1.5 ms, frequency 10 Hz) with the overall average output power of 2.3 mW (corresponding to the power amplitude of 153 mW) in one output beam at the wavelength of ~1055 nm. The actual pulse-duration was 87 ps.

Optical coherence tomography (OCT) is a powerful optical method, noninvasive and noncontact diagnostic method. Although it is usually used for medical examinations, particularly in ocular exploration; it can also be used in optical metrology as measure technique. In this work, we use OCT to measure thicknesses of films. In OCT, depth profiles are constructed by measuring the time delay of back reflected light by interferometry measurements. Frequency in k-space is proportional to optical path difference. Then the reflectivity profile is obtained by a Fourier transformation, and the difference between two successive peaks of the resulting spectrum gives the film thickness. Several films, food-type, of different thicknesses were investigated and the results were very accurate.

We present compact single photon lidar demonstrator dedicated for asteroid rendezvous missions. The instrument provides crucial data on altitude and terrain profile for altitudes exceeding 5km with a precision of less than 10 cm fulfilling the Rayleigh criterion. Transmitter and receiver optics designs are discussed, control and processing electronics based on a single rad-hard compatible FPGA (Field Programmable Gate Array) is analyzed. The FPGA electronics subsystems are TDC (Time-to-Digit Converter), laser trigger pulse generator and gate generator. Indoor calibration procedures of the whole demonstrator chain are proposed and evaluated. The calibration covers positioning of receiver and transmitter optics related to detector and laser, aligning of transmitter and receiver optical common paths. The retrieving strategy of terrain elevation profile is proposed and via indoor tests validated. Theory for surface slope and scanning is established, simulation and measurement results are compared and discussed.

In this paper the operation of pulsed diode-pumped Nd:GdVO4 laser oscillator in bounce geometry passively modelocked using semiconductor saturable absorber mirror (SAM), generating microjoule level picosecond pulses at wavelength of 1063 nm, is reported. Optimization of the output coupling for generation either Q-switched mode locked pulse trains or cavity dumped single pulses with maximum energy was performed, which resulted in extraction of single pulses as short as 10 ps and energy of 20 uJ. In comparison with the previous results obtained with this Nd:GdVO4 oscillator and saturable absorber in transmission mode, the achieved pulse duration is five times shorter. Using different absorbers and parameters of single pulse extraction enables generation of the pulses with duration up to 100 ps with the energy in the range from 10 to 20 μJ.

Examining the geometry of complex industrial free form objects, like a blade integrated disk (blisk) of a jet engine compressor, is currently subject to research. High measurement precision and speed are required and the complex geometry poses a challenge for state of the art measurement systems. In order to fulfill typical inspection requirements, the fringe projection methodology was adapted in this work to accomplish the task of fast and precise geometry examination. A low cost borescopic fringe projection system for 3D shape measurement based on consumer electronics combined with state of the art optics was developed. Nevertheless, it is able to provide measurement uncertainties comparable to professional systems. We are using a portable consumer LED-beamer, which we have modified to fit the optics of the borescope and a Raspberry Pi single-board computer with a 5 megapixel camera to capture the fringe patterns. With this setup and fringe projection algorithms, which have been developed by this institute over the last years, we were able to perform high quality measurements while still being suitable for a compact inspection system. Measurements with high point densities are possible even in narrow areas of parts with complex geometries like blisks. The measuring system and first measurement results will be presented at the conference.

A fiber-optic refractive index sensor based on surface plasmon resonance (SPR) in a thin metal film deposited on an unclad core of a multimode fiber is presented. The sensing element of the SPR fiber-optic sensor is a bare core of a step-index optical fiber made of fused silica with a deposited gold film. First, a model of the SPR fiber-optic sensor based on the theory of attenuated total internal reflection is presented. The analysis is carried out in the frame of optics of multilayered media. The sensing scheme uses a wavelength interrogation method and the calculations are performed over a broad spectral range. Second, in a practical realization of the sensor with a double-sided sputtered gold film, a reflection-based sensing scheme to measure the refractive indices of liquids is considered. The refractive index of a liquid is sensed by measuring the position of the dip in the reflected spectral intensity distribution. As an example, the aqueous solutions of ethanol with refractive indices in a range from 1.333 to 1.364 are measured.

Nowadays thermal plasma spray coating is widespread in automobile industry. For example, in the cylinder manufacturing process coatings are applied for friction reduction, wear and corrosion resistance. After the honing process, a coated surface exhibits porous microstructures, which are often characterized in order to understand functional correlations between key parameters of the pores and friction performance. In this paper, spatial point pattern analysis is used to investigate the pores’ distribution in a two dimensional space. Methods, such as nearest neighbor analysis and Ripley’s K-function, are used to conduct the experiments to analyze the observer’s pattern. Different edge correction methods in Ripley’s K-function are introduced. Confidence envelopes are simulated using the Monte Carlo method. Experimental results are presented to reveal the patterns of pores, where influences of the selected measurement area on the results are taken into account and further discussed.

The main advantage of an optoelectronic oscillator (OEO) is the ability to synthesize directly very high spectral purity frequency in microwave domain. Beside applications in radar, telecommunication and satellite systems, OEO can also be used in sensor applications such as refractive index or distance measurements. However, the long-term stability of the OEO is easily affected by ambient environment variations. The optical fiber loop effective refractive index varies corresponding to its surrounding temperature changes. Consequently, it makes the optical transmission path inside the fiber loop differ from the initial state, leading to oscillation frequency changes. To stabilize the single loop OEO, it is essential to keep its high Q elements in a well-controlled thermal box as much as possible. Unfortunately, in the real implementation condition, this requirement is difficult to be satisfied. In this paper, we present a new technique to estimate the oscillation frequency variation under the room temperature by using a vector network analyzer (VNA). Experimental results show a good correlation between OEO oscillation frequency drift and the phase measured by the VNA. This technique can be implemented to apply corrections when using the OEO as a distance variation or a refractive index measurement tool. We also tracked the temperature of the fiber loop at the same time with the VNAbased experiment to compare two correlations of temperature and phase with OEO oscillation frequency.

The kinetic parameters of a chemo-optical transducer layer sensitive to gaseous ammonia are characterized by means of attenuation total reflection method. The tested layer consists of cross-linked polydimethylsiloxane matrix sensitized by quinoline-based organometallic dye showing the selective chemical reaction with ammonia. Upper and lower limits of the ammonia diffusion coefficient and the ammonia-dye reaction constant are derived from the obtained experimental data and compared with other data available in literature and obtained from computer simulations.

A spectral-domain interferometric technique using the interference of polarization modes of a highly birefringent (HB) elliptical-core fiber to measure the temperature is presented. The method is based on the wavelength interrogation, i.e., the position of a chosen spectral interference maximum as a function of temperature is measured. Temperature sensing is carried out in a range from 300 to 370 K in an experimental setup comprising a white-light source, a polarizer, a delay line, a sensing HB fiber, an analyzer and a spectrometer. As the delay line, a birefringent quartz crystal of a suitable thickness is utilized to resolve a channeled spectrum in a range as wide as possible. A part of the sensing HB fiber, which is placed in a chamber, is exposed to temperature changes, and first, the polarimetric sensitivity to temperature is measured. It is revealed that the HB fiber is suitable for temperature sensing at a wavelength of 600 nm. Second, the shift of the wavelength position of the chosen spectral interference maximum with temperature is measured. It is revealed that the temperature sensitivity is higher at shorter wavelengths.

In the current paper the influence of the metallic nanoparticles trapped by arabinogalactan (AG) molecule on the AG refractive index is studied. A convenient approach for refractive index measurement by means of wavelength-domain interferometry is proposed.

We present optical fiber sensors to measurement strain and vibration. The sensors are based on fiber Bragg gratings (FBG). We prepared construction of strain sensors with respect to its implementation on the outer surface of concrete structures and with compensation of potential temperature drifts. These sensors are projected with look forward to maximal elongation and strength which can be applied to the sensor. Each sensor contains two optical fibers with FBGs. One FBG is glued into the sensor in points of fixation which are in the line with mounting holes. This FBG is prestressed to half of measurement range, than the stretching and pressing can be measured simultaneously by one FBG. The second FBG is placed inside the sensor without fixation to measure temperature drifts. The sensor can be used to structure health monitoring. The sensors to measurement vibration are based on tilted fiber Bragg grating (TFBG) with fiber taper. The sensor uses the TFBG as a cladding modes reflector and fiber taper as a bend-sensitive recoupling member. The lower cladding modes (ghost), reflected from TFBG, is recoupled back into the fiber core via tapered fiber section. We focused on optimization of TFBG tilt angle to reach maximum reflection of the ghost and taper parameters. In this article we present complete set-up, optical and mechanical parameters of both types of sensors.

This paper presents a method for active angular alignment of gauge block implemented in a system for automatic contactless calibration of gauge blocks designed at ISI ASCR. The system combines low-coherence interferometry and laser interferometry, where the first identifies the gauge block sides position and the second one measures the gauge block length itself. A crucial part of the system is the algorithm for gauge block alignment to the measuring beam which is able to compensate the gauge block lateral and longitudinal tilt up to 0.141 mrad. The algorithm is also important for the gauge block position monitoring during its length measurement.

Conditions of hydrogen loading were studied for shortening of the exposure time for fabrication of long-period fiber grating sensors using a low-pressure mercury lamp. By an increased hydrogen pressure of 135 atm, shortening of the exposure time to 2/3 that of 120 atm was obtained. By increasing the loading time from 4 to 12 weeks, the exposure time was shortened to 3/4 that of the same pressure, or half that of 120 atm for 3 weeks. The temperature rise of the fiber during exposure was measured to be 16 °C or less. Distribution of hydrogen molecules in the fiber was studied by a numerical analysis solving a diffusion equation. The result of the analysis agreed with the pressure dependence of the measured hydrogen concentration and the exposure time for fabrication. For the longer loading time, neither the calculated nor the measured hydrogen concentrations increased: the shortening of the exposure time by the longer loading time was not explained. The temperature and strain sensitivities were lower than those of hydrogen loading at 120 atm except that a temperature sensitive and strain insensitive long-period grating was obtained with a period of 460 μm.

We report on superlinear electroluminescent structures based on AlSb/InAs1-xSbx/AlSb deep quantum well grown by MOVPE on n-GaSb:Te substrate. Dependence of the electroluminescence (EL) spectra and optical power on the drive current in nanoheterostructures with AlSb/InAs1-xSbx/AlSb quantum well at 77 – 300 K temperature range was studied. Intensive two-band superlinear EL in the 0.5 - 0.8 eV photon energy range was observed. Optical power enhancement with the increasing drive current at room temperature is caused by the contribution of the additional electron-hole pairs due to the impact ionization by the electrons heated at the high band offset between AlSb and the first electron level Ee1 in the InAsSb QW. Study of the EL temperature dependence at 90 – 300 K range enabled us to define the role of the first and second heavy hole levels in the radiative recombination process. It was shown that with the temperature decrease, the relation between the energies of the valence band offset and the second heavy hole energy level changes due to the temperature transformation of the energy band diagram. That is why the EL spectrum revealed radiative transitions from the first electron level Ee1 to the first hole level Eh1 in the whole temperature range (90 – 300 K) while the emission band related with the transitions to the second hole level occurred only at T < 200 K.

Nowadays, the power cables are manufactured to fulfill the following condition – the highest allowable temperature of the cable during normal operation and the maximum allowable temperature at short circuit conditions cannot exceed the condition of the maximum allowable internal temperature. The distribution of the electric current through the conductor leads to the increase of the amplitude of electrons in the crystal lattice of the cables material. The consequence of this phenomenon is the increase of friction and the increase of collisions between particles inside the material, which causes the temperature increase of the carrying elements. The temperature increase is unwanted phenomena, because it is causing losses. In extreme cases, the long-term overload leads to the cable damaging or fire. This paper deals with the temperature distribution measurement inside the power cables using distributed temperature system. With cooperation with Kabex company, the tube containing optical fibers was installed into the center of power cables. These fibers, except telecommunications purposes, can be also used as sensors in measurements carrying out with distributed temperature system. These systems use the optical fiber as a sensor and allow the continual measurement of the temperature along the whole cable in real time with spatial resolution 1 m. DTS systems are successfully deployed in temperature measurement applications in industry areas yet. These areas include construction, drainage, hot water etc. Their advantages are low cost, resistance to electromagnetic radiation and the possibility of real time monitoring at the distance of 8 km. The location of the optical fiber in the center of the power cable allows the measurement of internal distribution of the temperature during overloading the cable. This measurement method can be also used for prediction of short-circuit and its exact location.

Optical fibers have been used in numerous sensing applications. Specifically, polymer-clad silica optical fibers have been employed for purposes of indirect chemical or biochemical sensors. These sensors are based on the interaction of guided light beams with extrinsic reagents immobilized in the fiber cladding. For this demand, it is necessary to enrich the fiber cladding with optical reagents with suitable optical properties without mechanical damage of cladding. Dipcoating and diffusion process have been studied and compared with respect to effective incorporation of appropriate quantities of selected organic reagents into polymer cladding. Short sections of sensitized optical fibers have been tested for potential using in ammonia fiber optic sensors.

Fiber optic distributed temperature sensing systems (DTS) are based on the principle of reflectometer and allow us to measure the temperature along the optical fiber. Optical fiber in these systems is used as a temperature sensor which can measure up to thousands of points simultaneously. DTS sensors use nonlinear phenomenon known as Raman scattering for temperature measurement. The advantages of this system include immunity to electromagnetic radiation, low cost of optical fiber, the possibility of measurement to a distance of 10 km and safe use in flammable or corrosive environments. The small size of optical fiber allows using in applications where the dimensions of the other sensors were problematic. A typical example of the DTS application is the fire detection in tunnels and buildings at risk, detection of water leaks on dikes and dams or monitoring of temperature in mine shafts. This article deals with the measurement of temperature transmission over various insulation layers using the DTS system. One of the problems of temperature transmission is that most of the sensors cannot measure the entire temperature profile but only allows a point measurement. This problem is solved by DTS systems with optical fibers. Optical fiber, due to its small size, can be applied among various insulation layers that were formed by rock wool. Three sensory layers formed by rings of multimode optical tightbuffered fiber with 50/125 micron core/cladding dimension were applied. The layers were linked together allowing a direct comparison of measured temperature. Rows of rings were placed on the margins and one was in the middle. Individual rings were linked together into the horizontal lines. Thus we were able to cover the whole surface of the insulation layers. Measurement was carried out in a closed air-conditioned room for 37 hours. Graphs with the progress of temperature at time and place were compiled from the measured data.

We have proposed a design and simulation of hardware realizations of smart multifunctional continuous logic devices (SMCLD) as advanced basic cells of the sensor systems with MIMO- structure for images processing and interconnection. The SMCLD realize function of two-valued, multi-valued and continuous logics with current inputs and current outputs. Such advanced basic cells realize function nonlinear time-pulse transformation, analog-to-digital converters and neural logic. We showed advantages of such elements. It’s have a number of advantages: high speed and reliability, simplicity, small power consumption, high integration level. The conception of construction of SMCLD consists in the use of a current mirrors realized on 1.5μm technology CMOS transistors. Presence of 50÷70 transistors, 1 PD and 1 LED makes the offered circuits quite compact. The simulation results of NOT, MIN, MAX, equivalence (EQ), normalize summation, averaging and other functions, that implemented SMCLD, showed that the level of logical variables can change from 0.1μA to 10μA for low-power consumption variants. The SMCLD have low power consumption <1mW and processing time about 1÷11μS at supply voltage 2.4÷3.3V.

Optical spectral analysis of the ultra-weak photon emission (UPE) could be utilized for non-invasive diagnostic of state of biological systems and for elucidation of underlying mechanisms of UPE generation. Optical spectra of UPE from differentiated HL-60 cells and yeast cells (Saccharomyces cerevisiae) were investigated. Induced photon emission of neutrophil-like cells and spontaneous photon emission of yeast cells were measured using highly sensitive photomultiplier module Hamamatsu H7360-01 in a thermally regulated light-tight chamber. The respiratory burst of neutrophil-like HL-60 cells was induced with the PMA (phorbol 12-myristate, 13-acetate). PMA activates an assembly of NADPH oxidase, which induces a rapid formation of reactive oxygen species (ROS). Long-pass edge filters (wavelength 350, from 400 to 600 with 25 nm resolution and 650 nm) were used for optical spectral analysis. Propagation of error of indirect measurements and standard deviation were used to assess reliability of the measured spectra. Results indicate that the photon emission from both cell cultures is detectable in the six from eight examined wavelength ranges with different percentage distribution of cell suspensions, particularly 450-475, 475-500, 500-525, 525-550, 550-575 and 575-600 nm. The wavelength range of spectra from 450 to 550 nm coincides with the range of photon emission from triplet excited carbonyls (350-550 nm). The both cells cultures emitted photons in wavelength range from 550 to 600 nm but this range does not correspond with any known emitter. To summarize, we have demonstrated a clear difference in the UPE spectra between two organisms using rigorous methodology and error analysis.

The ultra-weak photon emission (UPE) is a universal phenomenon common to all cells with active oxidative metabolism. Generally accepted mechanism of the origin of the ultra-weak photon emission considers reactions of radical or nonradical reactive oxygen species (ROS) with biomolecules such as lipids and proteins which lead to the formation of electron excited species. During the transition to the ground state the excess energy is released as a photon with a wavelength in the visible range of the electromagnetic spectrum. Since the intensity of the light is very low it is possible to be measured only by highly sensitive devices. We used Hamamatsu Photonics PMT module H7360-01 mounted into a light-tight chamber for the purposes of this work. The goal of our research is to delineate an origin of UPE from two model organisms; differentiated HL-60 cells (human promyelocytic leukemia) and yeast cells Saccharomyces cerevisiae. While the UPE from the yeast cells arises spontaneously during the growth without any external stimuli, UPE from HL-60 is induced by phorbol 12-myristate, 13-acetate (PMA). It is possible to modulate the UPE production by certain antioxidants which scavenge ROS formed during the metabolism (yeast cells) or respiratory burst (HL-60 cells). The experiments are focused on the description of effects caused by antioxidants. Several kinds of antioxidants (ascorbic acid, mannitol, glutathione) with different concentration were used and we studied the changes in the UPE intensities of and the temporal developments of the optical signal.

In this work the results of investigation of Cd_1-xMn_xTe (x=0.01, 0.03, 0.05) solid solutions synthesis and their thin films' obtaining technology have been represented. Epitaxial films of monocrystalline Cd_1-хMn_хTe semimagnetic semiconductors were obtained on mica substrate by MBC method. Lattice parameters and crystal structure of samples were defined with X-ray diffraction method. It has been studied the electrophysical parameters. Defect formation energy has been calculated for Cd_1-хMn_хTe semimagnetic semiconductors by Ab-initio method using Atomistix Toolkit program. We have studied the dependence of defect formation energy on supercell size for charged vacancy and interstitial defects in Cd_1-хMnхTe thin films.

This paper addresses OFDM (orthogonal frequency division multiplexing) transmission over optical links with high spectral efficiency, i.e. by using high-order QAM-modulation schemes as a mapping method prior to the OFDM multicarrier representation. Here we address especially coherent optical OFDM modem in long distance which is affected by a nonlinear distortion caused by fiber nonlinearity as a major performance-limiting factor in advanced optical communication systems. We proposed a nonlinear electrical equalization scheme based on the Volterra model. Compared with other popular linear compensation technique such as the LMS (least Mean Square) and RLS (Recursive Least square), simulation results are presented to demonstrate the capability of a Volterra model based electrical equalizer used in a coherent optical orthogonal frequency division multiplexing system. It is shown that the Volterra model based equalizer can significantly reduce nonlinear distortion.

This paper covers a description and a technique of a possible optical method of mode locking within a laser resonator. The measurement system is a part of instrumentation of laser-based experiment OSQAR at CERN. The OSQAR experiment aims at search of axions, axion-like particles and measuring of ultra-fine vacuum magnetic birefringence. It uses a laser resonator to enhance the coupling constant of hypothetical photon-to-axion conversion. The developed locking-in technique is based on differential interferometry. Signal obtained from the measurement provide crucial information for adaptive control of the locking-in of the resonator in real time. In this paper we propose several optical setups used for measurement and analysis of mutual position of the resonator mirrors. We have set up a differential interferometer under our laboratory conditions. We have done measurements with hemi-spherical cavity resonator detuned with piezo crystals. The measurement was set up in a single plane. Laser light was directed through half-wave retarder to a polarizing beam splitter and then converted to circular polarization by lambda/4 plates. After reflection at the mirrors, the beam is recombined in a beam splitter, sent to analyser and non-polarizing beam splitter and then inspected by two detectors with mutually perpendicular polarizers. The 90 degrees phase shift between the two arms allows precise analysis of a mutual distance change of the mirrors. Because our setup was sufficiently stable, we were able to measure the piezo constant and piezo hysteresis. The final goal is to adapt the first prototype to 23 m resonator and measure the displacement in two planes.

High requirements in terms of purity, quality, mechanical design and method of grinding are placed on the optical connectors. Connectors are mostly exhibited to the negative effects, such as temperature, humidity, dusty environments, etc. The effects of temperature on the optical fiber are already known and well described. However, the way in which the temperature change has effect on different types of connectors is not yet well understood and validated. Therefore it was necessary to find the answers within this article to the questions whether a change in temperature has the effect on the connector return loss and if so how big. The dependence of the attenuation coefficient on temperature change for the specific connector is also studied within the article. This allows determining how significant influence the choice of the type of ferrule on the return loss is. The three most commonly used types of connectors SC, FC and E-2000 with PC and APC polishing were selected. To describe the negative effects the dependence of return loss on temperature was chosen. The return loss was chosen because it is one of the key parameters that describes connectors and is measured in practice. Measuring instruments from EXFO model AXS-200/350 were used for the measurements. Measurements were carried out on single-mode fiber SMF 652.D at wavelengths of 1310 nm and 1550 nm. The transmission method was selected for the measurement. Measurements on each connector were performed 30 times and statistical model was compiled from the measured return loss.

Next-generation passive optical access networks come to the fore nowadays. These optical next-generation networks are the response to the increasing qualitative requirements from end users. Technologies using Time Division Multiplexing include NG-PON (XG-PON 1 and XG-PON 2) and 10GEPON. Their advantage is the applicability to older topologies, which are operated by the original technology of passive optical access networks. Wavelength Division Multiplexing Passive Optical Network (WDM-PON) is an alternative also belonging to next-generation networks. Time Division Multiplexing is in this case replaced by Wavelength Division Multiplexing. Certain variants of WDM-PON use a combination of broadband light source, optical circulator, optical phased array and tunable FP laser. Construction of the terminal units (ONU) is advantageous because it can always tune in to the appropriate wavelength in the given optical DWDM channel (100 GHz). The disadvantage is the increased security risk on the primary layer due to channel crosstalk in an optical phased array (AWG). The aim of this paper is to assess the degree of security risk in real conditions. The article includes both simulation and real measurements in C + L bands with 100 GHz DWDM spacing.

We report about a design of a bi-directional planar optical multiplex/demultiplex filter (triplexer) for the optical part of planar hybrid WDM bi-directional transceiver in fiber-to-the-home (FTTH) PON applications. The triplex lightwave circuit is based on the Epoxy Novolak Resin SU-8 waveguides on the silica-on-silicon substrate with Polymethylmethacrylate cladding layer. The triplexer is comprised of a linear butterfly concept of multimode interference (MMI) coupler separating downstream optical signals of 1490 nm and 1550 nm. For the upstream channel of 1310 nm, an additional directional coupler (DC) is used to add optical signal of 1310 nm propagating in opposite direction. The optical triplexer was designed and optimized using beam propagation method. The insertion losses, crosstalk attenuation, and extinction ratio for all three inputs/outputs were investigated. The intended triplexer was designed using the parameters of the separated DC and MMI filter to approximate the idealized direct connection of both devices.

The paper deals with the design of an micro-optical part of a WDM transceiver based on the circle volume holographic grating triplexer (VHGT) topology. The work is focused on detail description of the bidirectional micro-optical insertion system, especially on the coupling in the transmission direction of the WDM transceiver optical part. This micro-optical wavelength distribution system is imagine transmission system consisted of collimating cylindrical lenses set in the circle topology with the VHGT filter placed in the middle of the circle. The topology is described by ray matrices equations, calculated using analytic and numeric methods and optically measured. Considering simulation and measurement results of micro-optical insertion system the influence of these characteristics on ray path attenuation, diffraction efficiency and transceiver performance is estimated. The paper also discusses limits and conditions of the laser asymmetrical beam focus into the input/output optical fiber.

We propose a non Linear Wiener Hammerstein channel equalization algorithm for coherent optical OFDM system. The proposed equalization method compensates the channel non linearities. Simulations for the proposed non linear equalizer are conducted using a training sequence method to determine optimal performance through a comparative analysis. When compared to the un-equalized signals results show an improvement when using the Wiener Hammerstein equalizer. Moreover, it is shown that Wiener Hammerstein algorithm showed to be significantly beneficial for coherent optical OFDM systems. The performances of all different schemes were compared with respect to bit error rate, transmission distance, optical signal to noise ratio, power launch and error vector magnitude.

This paper presents the comparison of experimental characteristics of two types of Bragg fibers, one with a silica core and second with an air core. The claddings of the fibers consist of three pairs of Bragg layers. Each pair is composed of one layer with a high and one layer with a low refractive index with a refractive-index contrast of about 0.03. The diameter of the silica core is of about 30 μm and that of the air core is of about 55 μm. Preforms of the Bragg fibers in the form of a tube have been prepared by the MCVD method by using germanium dioxide, phosphorous pentoxide and fluorine as silica dopants. In the case of the fiber with the air core only Bragg layers were applied inside a substrate tube while in the case of the fiber with the silica core one additional silica layer was deposited over the Bragg layers. The fibers were drawn from the preforms under controlled temperatures in order to obtain fibers with air or solid cores. Results of characterization of prepared fibers by optical microscopy are presented. Several laser sources including a pulse and continuous-wave Nd:YAG lasers at 1064 nm and a laser diode at 1550 nm were used for testing the transmission of laser radiation through the fibers. Transmittances, attenuation coefficients, bending losses and spatial profiles of output beams from the fibers were determined from such measurements.

Laser diode module (LDM) became a commonly used light source, even when the interference pattern has to be created. Nowadays, fabricating a holographic grating is relatively a simple procedure. The two-beam interference took an important role among all of its applications. Nevertheless, the parameters of the interference grating depend on properties of the light source and recording medium used. On the contrary, a holographic grating may become a simple and useful tool to reveal real temporal coherence properties of widely used LDM and to determine frequency spacing when more longitudinal modes are generated.

Deformable mirrors have gained increasing interest in many different fields of application including laser physics, and they are becoming a universal tool for correcting optical aberrations of laser beams especially in large scale laser systems. One of the most common types of deformable mirror is a bimorph design which uses two plates of piezomaterial to which single electrodes are connected. These electrodes form the actuator array and their layout defines the resulting performance of the mirror to some extent. In the end all types of deformable mirrors currently used use an actuator array of some sort. To estimate the significance and effect of different actuator layout and shapes of actuators, an experimental study was performed. Four different commonly used actuator arrays were compared using photo-controlled deformable mirror. Using such device allows to study the effect of actuator layout separately from all other effects, since the device remains the same including all its imperfections. The experimental results are compared with numerical simulations and discussion is presented.

In our laboratory, we deal with characterization of diffraction gratings produced in photopolymers. In such recording systems, the diffraction of light is induced via spatial modulation of refractive index and the diffraction efficiency of transmission gratings can reach values close to 100% due to relatively high values of this modulation. Depending on the exposure condition, the refractive index modulation can reach higher value than its optimum and the efficiency drops. This is an unwanted effect. It is called an overmodulation and it is relatively complicated to find out whether under- or over- modulation occurs. To measure and evaluate this overmodulation effect in transmission gratings we propose a simple method based on multiple/two-wavelength measurement of diffraction efficiency. In this contribution, we would like to present the theoretical idea of the method and also experimental results obtained on photopolymer Bayfol HX.

The eigenfunctions of optical operator describing a finite two-lens imaging system are considered accounting for a radial symmetry. Obtained functions are analogue of the generalized spheroidal functions, which are eigenfunctions of finite Hankel transform. A peculiarity of the considered calculations of the bounded lens system is in accounting for the system’s physical characteristics. A possibility of formation of a radially symmetrical optical signal, which transfers without distortions as a superposition of eigenfunctions matching the parameters of the optical system, is demonstrated. Gaussian-beam transfers through the imaging systems with circular and with rectangular apertures are compared.

A helical intensity distribution was created in a near-field when Gaussian laser beam was focused by a binary phase spiral axicon with high numerical aperture. It was shown by 3D-simlation using the Comsol software and natural experiments with near-field microscope NT-MDT Integra Spectra. Experimental measurements and numerical simulations are in good agreement.

In this contribution we present a new family of diffractive lenses which are designed using the m-bonacci sequence. These lenses are a generalization of the Fibonacci Zone Plates previously reported. Diffractive elements of this type are called aperiodic zone plates because they are characterized by a radial profile that follows a given deterministic aperiodic sequence (Cantor set, Thue-Morse, Fibonacci...). Aperiodic lenses have demonstrated new interesting focusing and imaging properties that have found applications in different fields such as soft X-ray microscopy and spectral domain optical coherence tomography. Here, we show that m-bonacci zone plates are inherently bifocal lenses. We demonstrate that the relative separation of their foci depends on the m-value of the sequence and also can be correlated with the generalized golden ratio. As a particular case, the properties of the m-bonacci sequence with m=2 and m=3, called Fibonacci and Tribonacci Zone Plates respectively are discussed.

Two-step field-assisted ion-exchanged waveguides have been fabricated on a glass substrate. The concentration profiles of the exchanged ions were measured with electron microprobe. The waveguides were characterized under scanning electron microscope and optical microscope for the investigation of burying structures. Guiding mode patterns were characterized with near-field measurement, where symmetric profiles were observed for the burying-type waveguide. The refractive index profiles were also measured with a modified end-fire coupling method. The relation between ion concentration profiles and index profiles were compared for the waveguides with different fabrication process.

Propagation of ultrashort pulses in dispersing media and optical fibers is calculated and analyzed. An analytical expression for the electric field of ultra short pulse after propagating certain distance z is derived in the second order dispersion theory. The propagation of a Gaussian pulse is considered.

In this work we report on the fluorescence lifetime characterization of the experimentally prepared Tm-doped silica optical fibers with increased quantum conversion efficiency (QE). Optical fibers were drawn from preforms prepared by conventional solution-doping of thulium and aluminium chlorides and by deposition of dispersed alumina nanoparticles with thulium chloride. Prepared preforms and optical fibers were characterized by means of thulium and aluminium concentrations, refractive index profiles, optical spectral attenuations (absorptions) and fluorescence lifetimes. Highly aluminium-codoped optical fiber prepared from alumina nanoparticles exhibited fluorescence lifetime of about 690 μs, which is about 40% higher compared to the conventionally prepared Tm-doped silica fiber.

Femtosecond lasers have become a powerful tool for 3D space-selective crystallization of glasses. A laser-induced cumulative heating effect required for crystal growth is usually considered to take place only at pulse repetition rate over 100 or 200 kHz and 200 kHz is known as the lowest repetition rate at which femtosecond laser-induced crystallization has been reported so far. We for the first time demonstrate precipitation of LaBGeO5 crystals in lanthanum borogermanate glass using a femtosecond laser emitting 1030 nm, 300 fs, 110 μJ pulses with adjustable repetition rate below 100 kHz. For the applied laser, minimal repetition rate enabling nucleation of ferroelectric LaBGeO5 crystals inside the glass was shown to be 9 kHz at maximal pulse energy of 110 μJ and growth of a crystalline line from the formed seed crystal was obtained starting from 8 kHz though smooth homogeneous oriented line which might be regarded as quasi-single-crystalline could be grown at 25 kHz or higher and corresponding pulse energy of 18 μJ. Thus, the pulse repetition rate sufficient for a cumulative heating effect and a stable crystal growth was reduced by an order of magnitude as compared to earlier publications due to relatively high pulse energy. Possibility and efficiency of cumulative heating and crystal growth and average time required for forming the seed crystal have been studied for various combinations of the pulse energy and the repetition rate. Obtained crystalline features have been studied by micro-Raman spectroscopy and Raman mapping which confirmed growth of stillwellite-like LaBGeO5 phase and orientation of its polar axis along the direction of the crystalline line.

The paper presents results on preparation and characterization of highly reflective coatings on planar substrates and inside silica tubes. Coatings are designed for a maximum reflectivity at a wavelength of 550 nm and consist of several pairs of oxide layers. Each pair is composed of one layer with a high refractive index and one layer with a low refractive index with a refractive-index contrast of about 1.1. The layers were prepared by the sol-gel method. High-index layers were applied from a sol based on titanium butoxide while a sol of tetramethoxysilane was use for low-index layers. The sols were deposited onto silica slides or onto walls of silica tubes by using the dip-coating technique. Applied gel layers were thermally treated at temperatures up to 450 °C in order to obtain densified layers with thicknesses 50-100 nm. Coatings with one to five pairs of layers were fabricated. Prepared coatings were characterized by transmission and reflection spectrometry in a wavelength range from 190 to- 1100 nm, by contact profilometry, and by spectral ellipsometry. Thicknesses and refractive indices of coatings were determined from these measurements. For normal light incidence a reflectivity higher than 99% in a wavelength range of 500-650 nm was measured by transmission spectrometry on coatings prepared from four or five pairs of layers. Similar reflectivity values were determined for angles of incidence of 15, 30, 45 and 60 degrees by using reflection spectrometry. Transmission spectra measured on the coated tubes which show interference bands are also presented in the paper.

Optical fibers with non-circular cross-sections can be effectively used for pumping of fiber lasers and amplifiers. Noncircular fiber-optic structures can be also employed for a control of propagating light polarization. Details of preparation of three types of optical fibers with non-circular cross-sections are presented. A polarization-maintaining (PM-) fiber with elliptical core was drawn from non-circular preform to study the effect of drawing temperature onto the fiber geometry. A stabilization of fiber rotation during the drawing was successfully tested during preparation of double-clad (DC-) optical fibers with hexagonal and special tailored cross-sections. The conservation of original geometry during the drawing was examined.

Chalcogenide glasses based on arsenic sulfide (As2S3), arsenic selenide or telluride are known to exhibit high optical nonlinearities which are necessary for advanced applications in telecommunications. Both, standard optical fibers and microstructured fibers have been fabricated from chalcogenide glasses. In this paper we deal with As2S3 solid core fibers and capillary fibers coated with a polymer jacket of UV acrylate. The guiding mechanism employing the reflection on boundary of high-index glass (a refractive index of about 2.4) and hollow cavity (n=1) was confirmed by ray-optic calculations. Fibers were drawn from input As2S3 rods and tubes. The rods were prepared from extra pure arsenic and sulfur by their melting in an evacuated ampoule. The tubes were prepared by using rotational melting technique in an evacuated ampoule rotating at 1600 rpm. Rods and tubes were elongated into fibers by using a fiber drawing facilities for preparation of optical fibers from soft optical glasses. Temperatures in a range 300-400 °C and drawing velocities of about 0.1 m/s were used. Fibers were prepared either without any polymeric jacket or they were provided by a jacket of UV acrylate (n ∼ 1.5). Fibers with diameters from 0.2 to 0.4 mm were fabricated. Dimensions of prepared fibers were measured by optical microscopy without prior polishing. Transmission properties of prepared fibers were characterized by measuring angular distributions of output power at the wavelength of 670 nm. Optical losses of fibers exceeding 2 dB/m were determined by using the cut back method.

Design, fabrication and RNF measurement of the optical multi-mode interference power splitter 1 to 2 with graded refractive index is reported. The design was developed by utilizing numerical solutions using the finite difference beam propagation method for operation wavelength 1550 nm. The deposition tests that led to the fabrication of the proposed structures were made after designing the structures. Several samples of optical MMI splitters 1x2 were obtained by Ag+↔Na+ two step field assisted ion exchange process in molten salt into a new special optical glass substrate for ion exchange technology. The refractive index profile of the channel waveguide was verified by the direct measurement near-filed method by the Refractive Near Field Profilometer.

This paper is dealing with design of new type of optical transmitter that is composed of bundle of optical fibers. For design purposes multimode fibers with different dimensions 50/125 and 62.5/125 µm were used. Software designs consisting of 3 or 5 optical fibers in bundle were subsequently evaluated from the point of view of uniform optical intensity distribution and dimensions of light pattern in space.

Femtosecond laser-induced modification of Au-doped phosphate glass at different pulse repetition rates using an Yb femtosecond amplifier emitting pulses of up to 120 μJ energy at 1030 nm with adjustable repetition rate up to 100 kHz is presented. At the repetition rate as low as 1 kHz, only refractive index modification and formation of red color centers are observed. Increasing the average output laser power resulted in increase of color intensity, but this color could be easily erased by the heat treatment at 300˚C for 20 min indicating athermal nature of these laser-induced effects. By contrast, at the repetition rate from 25 kHz to 100 kHz, cumulative heating effect was demonstrated and allowed to realize for the first time one-stage laser-induced growth of Au nanoparticles in the solid glass accompanied by the appearance of a thermally stable red color. Z-scan analysis of nonlinear properties of the studied glass samples is carried out. Details of Au nanoparticles growth and phosphate glass modification by the tightly focused femtosecond laser beam are discussed.

We propose an all-optical fiber-based device able to accomplish both polarization control and OSNR enhancement of an amplitude modulated optical signal, affected by unpolarized additive white Gaussian noise, at the same time. The proposed noise cleaning device is made of a nonlinear lossless polarizer (NLP), that performs polarization control, followed by an ideal polarizing filter that removes the orthogonally polarized half of additive noise. The NLP transforms every input signal polarization into a unique, well defined output polarization (without any loss of signal energy) and its task is to impose a signal polarization aligned with the transparent eigenstate of the polarizing filter. In order to effectively control the polarization of the modulated signal, we show that two different NLP configurations (with counter- or co-propagating pump laser) are needed, as a function of the signal polarization coherence time. The NLP is designed so that polarization attraction is effective only on the "noiseless" (i.e., information-bearing) component of the signal and not on noise, that remains unpolarized at the NLP output. Hence, the proposed device is able to discriminate signal power (that is preserved) from in-band noise power (that is partly suppressed). Since signal repolarization is detrimental if applied to polarization-multiplexed formats, the noise cleaner application is limited here to "legacy" links, with 10 Gb/s OOK modulation, still representing the most common format in deployed networks. By employing the appropriate NLP configurations, we obtain an OSNR gain close to 3dB. Furthermore, we show how the achievable OSNR gain can be estimated theoretically.

The contribution deals with the influence of DFB laser light on spectral properties of coherent and noncoherent sources. DFB laser, FP laser and surface emitting LED have been as the directed light sources. All sources operated at wavelengths around 1550 nm. As a master DFB laser the tunable laser within range of wavelengths from 1510-1610 nm has been applied. The connection of light sources was carried out with the help of fiber optical couplers 2x2 with division ratio 50:50. The spectral properties of directed light sources were searched in dependence on wavelength changes of tunable laser source. Besides of wavelengths, the optical power of tunable laser has been changed in range - 0,25 dBm – 0 dBm. All changes within directed light sources were searched for various values of driving currents. It was verified experimentally that the mutual interaction DFB-DFB lasers is minimal, the influence of optical power coming from master DFB laser appeared as neglected. Several effects manifested during mutual interaction between master DFB laser and directed FP laser. In this case the intense changes in optical power of particular modes were observed. Some modes had suppressed their powers some modes were dominantly excited. These changes could be the basis for construction of all optical switches or for devices making logical functions. Important spectral changes were also observed in case of mutual interaction between DFB master laser and directed surface emitting LED.

This paper deals with evaluation and processing of astronomical image data, which are obtained by a wide-field all-sky image analyzing monitoring system (WILLIAM). The WILLIAM is an additional experimental camera for project MAIA equipped with wide field lens. The system can detect stellar objects as faint as 6th magnitude. Acquired image data are processed by an algorithm for stellar object detection and identification which is based on coordinates transfer function. Cartesian coordinates at the image data are transformed to horizontal coordinate system. This coordinate system allows searching in astronomical catalogues of stellar objects. This paper presents the components of WILLIAM, its measured electro-optical characteristics and some results of identification.

We proposed and demonstrated an all-optical triode based on a tandem wavelength converter using cross-gain modulation (XGM) in semiconductor optical amplifiers (SOAs). Negative feedback optical amplification scheme, which has the key advantages of reducing bit error rate and waveform reshaping at the output, was employed in this optical triode. This scheme utilizes an input signal and a negative feedback signal (a signal with reverse intensity to the input) and they were fed together into the optical amplifier. Manipulating the intensity of negative feedback signal enabled the noise suppression effect to be optimized and the outputs recorded improvements in bit error rate (BER) and also undergone waveform reshaping shown by the eye-pattern. In negative feedback optical amplifier, the negative feedback signal and input signal were fed into the SOA. However, due to XGM mechanism, there is a setback in which both signals could not be simultaneously fed. Therefore, by using an optical delay, negative feedback timing was manipulated and we investigate timing characteristics of negative feedback optical amplifier with BER and eye-pattern waveforms at 10 Gb/s.

Fiber Bragg gratings (FBGs) are novel and promising devices for all-optical switching, ADD/DROP multiplexers, AND gates, switches, all-optical memory elements. Optical switching based on optical Kerr effects induced with high pump laser light incident on the FBGs cause the change of spectral characteristics of grating depending on the incident power. In this paper numerical studies of the nonlinear FBGs are presented. Optical switching based on the optical bistability in nonlinear chalcogenide FBGs is investigated. The spectral response of nonlinear FBGs is discussed from theoretical viewpoint. The simulations are based on the nonlinear coupled mode theory.

This paper presents the progress in the development of two Fabry-Pérot filter cavities for repetition rate multiplication of two femtosecond frequency combs. The optical design of both setups consists of mode matching optics and a resonant cavity for the repetition rate multiplication. In one case, the cavity consists of two dielectric mirrors with near-zero group velocity dispersion and in the other of two silver coated mirrors. We demonstrate multiplication of a 1 GHz repetition rate to 10 GHz for a Ti:Sa femtosecond frequency comb with central wavelength around 820 nm and of 250 MHz repetition rate to 1 GHz for a Er-doped fiber femtosecond frequency comb with central wavelength around 1560 nm.

The paper deals with the successive localization and imaging of solar cell defects, going from macroscale to microscale. For the purpose of localization, the light emission from reversed bias samples is used. After rough macroscopic localization, microscopic localization by scanning probe microscopy combined with a photomultiplier (shadow mapping) is performed. The type of microscopic defects are discernable from their current-voltage plot or from noise measurements. Two specific defects, both of the avalanche type, with different voltage threshold, are presented in this paper. Current voltage plots and radiant flux versus voltage characteristics for two temperatures, topography, shadow map and corresponding SEM micrographs are shown for both samples.

Ag nanocluster-doped glasses have been prepared by a conventional melt-quenching method. The effect of melt temperature and dwell time on the formation of Ag nanoclusters and Ag nanoparticles in simple host oxyfluoride glasses has been studied. The increase of melt temperature and dwell time results in the dissolution of Ag nanoparticles and substantial red-shift of absorption and photoluminescence spectra of the prepared glasses. The quantum yield of the glasses is ~ 5% and does not depend on melt temperature and dwell time. The prepared glasses may be used as red phosphors or down-conversion layers for solar-cells.

We report on detection and localization of imperfections in silicon solar cell bulk and surface with sub-micrometer resolution. To obtain this resolution, a family of imaging techniques including SNOM, SEM and AFM is often separately used for this purpose. In this paper we combine several of these proximal methods together, because each of them brings complimentary information about the imperfection. First, we note that SNOM images often contain distortions due to the interaction of the probe tip and sample. Therefore, we look for the possibility to circumvent this weakness and obtain more realistic images. In our experiments, we take advantage of the fact that defects or imperfections in silicon solar cell structures under reverse-bias voltage exhibit microscale low light emitting spots, and we apply an improved SNOM measurement to localize these spots. As a result, this system allows a localization and measurement of low light emission on microscale. Consequently, the size and shape of imperfections can also be determined.

Bright white light sources are of significant importance for automotive front lighting systems. Today’s upper class systems mainly use HID or LED light sources. As a further step laser diode based systems offer a high luminance, efficiency and allow the realization of new dynamic and adaptive light functions and styling concepts. The use of white laser diode systems in automotive applications is still limited to laboratories and prototypes even though announcements of laser based front lighting systems have been made. But the environment conditions for vehicles and other industry sectors differ from laboratory conditions. Therefor a model of the system’s thermal behavior is set up. The power loss of a laser diode is transported as thermal flux from the junction layer to the diode’s case and on to the environment. Therefor its optical power is limited by the maximum junction temperature (for blue diodes typically 125 - 150 °C), the environment temperature and the diode’s packaging with its thermal resistances. In a car’s headlamp the environment temperature can reach up to 80 °C. While the difference between allowed case temperature and environment temperature is getting small or negative the relevant heat flux also becomes small or negative. In early stages of LED development similar challenges had to be solved. Adapting LED packages to the conditions in a vehicle environment lead to today’s efficient and bright headlights. In this paper the need to transfer these results to laser diodes is shown by calculating the diodes lifetimes based on the presented model.

The electroluminescent properties of an n-GaSb/n-InGaAsSb/p-AlGaAsSb heterostructure with a high potential barrier in the conduction band (large conduction-band offset) at the n-GaSb/n-InGaAsSb type-II heterointerface (ΔEc = 0.79 eV) are studied. Two bands with peaks at 0.28 and 0.64 eV at 300 K, associated with radiative recombination in n-InGaAsSb and n-GaSb, respectively, are observed in the electroluminescence spectrum. In the entire temperature range under study, T = 290 – 480 K, additional electron-hole pairs are formed in the n-InGaAsSb active region by impact ionization with hot electrons heated on the large the conduction-band offset. These pairs contribute to radiative recombination, which leads to a nonlinear increase in the electroluminescence intensity and output optical power with increasing pump current. A superlinear increase in the emission power of the long-wavelength band is observed upon heating in the temperature range T = 290 – 345 K, and a linear increase is observed at T < 345 K. Theoretical calculations have shown that this behavior of the temperature dependence of the optical power caused by competition between the radiative recombination, thermionic emission and Auger recombination.

The objective of the study is to characterize the dependence of the optical properties of solid solutions of silicon carbide and aluminum nitride on composition. Even small differences in composition provide manipulation of band gap features over a wide range. Data for this paper were collected by X-ray diffraction, photoluminescence and absorption spectroscopy. The evolution of the observed optical properties as a result of compositional changes were studied. X-ray studies confirm the presence of a(SiC)_1-x(AlN)_x solid solution. Investigation of absorption spectra shows the optical band gap of the sample with composition (SiC)_0,88(AlN)_0,12 is 3.5eV, and 4.24 eV for the (SiC)_0,36(AlN)_0,64 solid solution. The photoluminescence spectra demonstrate the strong dependence of the spectra on composition x. The experimental results are in agreement with theory. These data demonstrate the optimization of optical properties for particular optoelectronic applications by varying the (SiC)_1-х(AlN)_х composition.

The combination of single photon emitters (quantum dots) and tailored metal nanoparticles with defined size and shape allows a detailed study of the interaction between light and matter. The enhanced optical near-field of the nanoparticles can strongly influence the absorption and emission of nearby fluorescent quantum dots. We show that a controlled spatial arrangement enables the analysis and understanding of polarization dependent coupling between a metal nanoparticle and few or single fluorescent quantum dots. Modifications in the fluorescence spectrum and lifetime are analyzed and compare well with simulations. The reduction of the fluorescence lifetime in such systems is usually in the order of 3-10. However, much larger reductions are to be expected if the quantum dots are positioned in a nanometric gap between two plasmonic nanoparticles, eventually leading to hot luminescence. We approach this regime experimentally and present first results from lithogaphically fabricated gold particle-pairs with controlled gap widths in the range of 1-20nm.

A rigorous numerical analysis is performed in order to discuss and reveal mechanisms responsible for the extraordinary transmission through 1-D and 2-D sub-wavelength arrays of infinite slits and holes, respectively. The investigation is mainly focused on the influence of structural parameters on the resonant enhancements of optical response in the sub-wavelength region. Zero-order transmission maps are calculated in the array periodicity and slit/hole filling factor plane where a behaviour of the existing modes can be clearly resolved. The effect of metallic film thickness is also considered. Identification of mode resonances playing a significant role in the EOT process is verified by studying the corresponding field profiles. It is found that for TE polarization in the case of 1-D periodic metallic array, the TE fundamental mode plays a significant role in the enhanced energy transfer, however, for TM polarization, TEM modes are responsible for energy transfer through one-dimensional infinite slits. Together with waveguide / cavity resonances investigation, surface plasmon-polariton excitations are studied, and their contribution is discussed in the connection to the enhanced transmission. For the case of 2-D array, map of modes, based on the propagation constants and the coefficients of attenuation, is constructed in order to identify the group of those modes strongly contributing to the EOT. Importantly, metal is not considered as a perfect conductor.

We study theoretically the angular momentum transfer between strongly focused laser vortex beam and a dielectric oblate spheroidal particle (OSP). We find sets of geometrical parameters of the particle and the beam for which the particle is stably trapped on the beam axis in a uniform rotating state, thereby serving as a possible test probe of the global beam angular momentum as well as its spin and orbital parts.

We have elaborated substrates for surface enhanced Raman scattering (SERS) based on carbon nanowalls (CNW) deposited with Ag nanoparticles and thin Ag films. For carbon nanowalls deposited with silver nanoparticles, the achieved analytical enhancement factor SERS was from 50 to 2500. Much higher analytical enhancement factor of SERS, up to 5×10⁴, was obtained for carbon nanowalls deposited with thin Ag film. In this case the SERS signal is determined by fractal structure of carbon nanowalls covered by Ag films. Such fractal structure provides a strong inhomogeneous localization of light, formation of a large number of hot spots and leads as a result to significant enhancement of SERS signal.

Imaging of surface textures requires many combinations of incident illumination angles and detector angles of view. Kaleidoscope is one of the means for measurement of bidirectional texture function of various sample surfaces. An optical system featuring the kaleidoscope is proposed in the paper. Optical parameters of such an imaging system are described and evaluated. We also discuss the optimization process of these parameters which influences the overall imaging performance of a kaleidoscope device. We provide the visualization of various kaleidoscope designs.

Tendencies of international cooperation in engineering education became very visible during recent years. We demonstrate this statement on one currently running EU project ADOPSYS in the field of optical design, which is an important part of engineering education in photonics. This example shows the importance of the input from different countries and organizations - both from industry and academia. Seven universities and eight optical companies are involved in the project ADOPSYS. Sharing experience of Academia education activity we provide new international type of education “free-of borders”. We are going to discuss the key enable technology – PHOTONICS, which is widely used in modern society. Engineering science became very international. For communicating between people from different countries the English language is now used almost exclusively. For a fruitful collaboration between people from different nations, in multi-national projects, tolerance and respect are required between people of different political, cultural, educational backgrounds.