Diffraction mathematical theory of light can be derived from Quantum Mechanics and Relativity. Using the duality between position and momentum variables, we show that the momentum distribution of light coincides with the well-known angular spectrum distribution. The momentum distribution links quantum theory and relativity to classical diffraction theory. We also show that the Huygens Principle and the momentum distribution are conjugate expressions at the diffraction aperture. These considerations lead to the geometrical theory of diffraction.

In this paper we describe two approaches for extending the depth of field in incoherent imaging system. The first one, a hybrid opto-digital incoherent imaging system, relies on an optical setup whereby the image is deliberately distorted, followed by a digital restoration stage. The second, an all-optical incoherent imaging system is based on a spatially code multiplexed multiple Fresnel lens mask, poisitioned in the lens aperture. Both provide a relatively high optical throughput and small contrast reduction, for an extremely wide range misfocus positions. For both cases, design considerations for an extended depth of field will be described. It is important to mention that both approaches are able to provide results in real time, thus enabling their usage in practical systems; yet the all-optical system presents a remarkable simplification.

The main advantage of optical image processing with respect to its electronic counterpart is the high degree of parallelism. This characteristic can be boosted by feeding an optical system with several channels simultaneously. Several ways to perform this multiplexing can be devised. In this talk we focus on the spatial multiplexing, were several channels share the spatial bandwidth of the system input and wavelength multiplexing, were the channels are input in different wavelengths simultaneously. Principle and applications are discussed, along with several possible architectures for image processing systems.

New feasibilities are considered for optical correlation diagnostics of rough surfaces with different distributions of irregularities. The influence of deviations of the height surface roughness distribution from a Gaussian probability distribution on the accuracy of optical analysis is discussed. The possibilities for optical diagnostics of fractal surface structures are shown and the set of statistical and dimensional parameters of the scattered fields for surface roughness diagnostics us determined. Finally, a multifunctional measuring device for estimation of these parameters is proposed.

Quality control of integrated circuits using pattern recognition is usually carried out in a controlled environment. Colored pigments on the serial numbers of chips cause variations of intensity of the reflected light. So there is a need for methods to detect targets independently of the illumination. We apply a technique that yields correlation peaks that are invariant under a linear transformation of object intensity, for the detection of chips on integrated circuits. The method can identify the chip, detect if the chips are present or absent, if it is the wrong chip and if it is placed and oriented correctly.

Our paper concerns with statistical processing of digitally recorded straight equispaced fringe patterns. We determine the highest degree of accuracy that can be achieved in estimating fringe parameters by statistical processing in given statistical fluctuation conditions affecting the recorded image.

A color similarity test was conducted on the 24 color patches of a Gretag Macbeth color checker. Color similarities were measured either by distances between standard colorimetric representations (such as RGB, Lab or spectral reflectance curves) or by human observer judgments. In each case, the dissimilarity matrix was processed by a classical, metric, multidimensional scaling algorithm, in order to produce a visually-interpretable two-dimensional plot of color dissimilarity. The analysis of the plots produces some interesting conclusions. First, the plots produced by the Lab, RGB and spectral representations exhibit very evident variation axes according to the luminance and basic chromatic differences (red-green, blue-yellow). This behavior (trivial for the Lab representation) suggests that the color similarity measurement by chromatic differences is implicitly embedded in the RGB and spectral representations. The color dissimilarity plots associated to the human judgments (for any individual, as well as for an “average” observer) exhibit a different organization, which mixes hue, saturation and luminance (HSV). According to these plots, the human similarity judgment is not entirely HSV-based. We prove that it is possible to obtain the same color dissimilarity plots if a fuzzy color model is assumed. The fuzzy color model provides similarity coefficients (similarity degrees) between pairs of colors, based on their inter-distance, according to an imposed “color confusion” control parameter, which seems to be relevant for the human vision.

Fourier transform profilometry, a well-known technique to obtain images of three-dimensional (3-D) objects, is used to achieve a real-time optical recognition of 3-D objects. A distorted grating pattern, that carries all the 3-D information of the object, is obtained from the projection of a regular fringe pattern onto the 3-D object surface. The analysis of such patterns is the basis of the optical method for recognizing 3-D objects in real time. The performance of the technique is demonstrated in two different types of correlators: the joint transform correlator and the classical convergent correlator. The proposed method is extended to the rotation-invariant and scale-invariant 3-D optical recognition. As is shown, the whole experimental setup can be constructed with simple equipment. Some experimental results, which demonstrate the ability of the method, are presented.

This work is devoted to the elaboration of complex polarization-correlometry and wavelet-analysis of object laser fields, formed by the structured biotissues with the following working out the principles of optical diagnostics of their physiological state. The histological sections of physiologically normal muscular tissue of the rats’ heart (group A) and necrotically (infarct) changed one (group B) have been investigated.

In this paper we use a logarithmic model of image representation for gray level image enhancement. We begin with a short presentation of the model and then, the formulas for the mean dynamic range. After that we present two image transforms: one performs an optimal enhancement of the mean dynamic range using the logarithmic addition, and the other does the same for positive and negative values using the logarithmic scalar multiplication. We present the comparison of our results with the results obtained using classical image enhancement methods like gamma correction and histogram equalization.

In the situations where the classic refractometry methods cannot be applied, the immersion methods are used. Phase contrast microscopy is one of the methods that make evident the difference between the refractive index of an immersed sample and the refractive index of the immersion medium. The measurement of the refractive index of the sample is performed by changing under control the refractive index of the immersion medium, until this becomes equal to the index of the sample. The present work is aiming to answer to a series of questions concerning the performances that a system composed of a phase contrast microscope equipped with a CCD camera and a temperature control device should achieve in order to measure the refractive index with a prescribed measurement error. The possibilities of measurement of the refractive index by means of the controlled heating of the sample-immersion system assembly and by means of changing the concentrations of the components of the immersion medium are examined.

X-ray diffraction has a wide applicability as regards the analytical studies of ancient artifacts and is often combined with other methods of investigation such as: bulk chemical analyses, chemical-extraction techniques, and x-ray microanalysis in order to determine aspects regarding sources of raw materials, made technology, trade routes in prehistoric times.

The paper is focused on the behavioral simulation of the mineral and organic lenses, defined by geometric characteristics (the accumulation radius, thickness, diameter) [2] and material characteristics, for a certain incident wavelength [2]. The simulation provides a picture of the ray-tracing for the second and third reflection/refraction. At the same time, the user can display the print of a ray on a normal plane related to optical axis direction. The authors designed the simulation program, aimed to evaluate the wounded through the multiple reflections in the spectre available for chosen material. On this way, the disparity of a certain parameter will influence the transference through lenses for some radiation or spectre. The paper is designed to be used in optics, to shape the refractive/reflective components, and can predict the useful diameter of lenses, diaphragms or aperture stop; the paper is a guide for qualified professors to simulate the route of telecentric fascicle, after multiple reflection and refraction, to illustrate Snell’s law, all of them by changing the optical and geometrical characteristic of lenses.

This paper is devoted to the analysis and experimental testing of the concept of laser polarization biotissue probing. The methods of increasing the signal-to-noise ratio in coherent images of the optically anisotropic architectonics of the morphological biotissue structure are considered. The possibilities of polarization selection and contrasting of such images screened by other biotissues are examined. The influence of the depolarization degree of the scattered background on the signal-to-noise ratio is investigated. The possibilities of polarization correction of the probing beam for contrasting biotissue images are analyzed.

The possibility of the vortexless optical traps and self-converging optical traps formation on the base of technique of computer generated holograms is considered. Two methods of the creation of self-converging optical traps are proposed. First of them is based on the transforming of the vortexless optical trap. The second of them is based on the formation of special kind of elementary polarization singularities. The principles of the formation of s-contours with optimal characteristics are formulated. The results of computer simulation and experimental modeling are presented.

The use of optical correlation for pattern recognition represents a strong tool when high speed and accurate signal processing is required. On the other hand, the product security requires new sophisticated elements in order to avoid the product counterfact. Following this idea a method based on phase masks has been proposed in the last decade to allow card security. Recently, the validation of the security phase masks has been implemented optically in a joint transform correlator. The reference mask and the mask to be validated are introduced in the same object plane and the optical Fourier transform is performed simultaneously for both of them. The spectrum intensity is then processed digitally by a PC to evaluate the correlation signal between the reference and the card to be validated. In this paper we present some considerations regarding the optimal setup for card validation and the use of phase masks combined with amplitude masks.

A novel method to design diffractive optical elements, based on the spherical wave propagation and superposition, is presented in this paper. Underlying theory, practical considerations, results and limitations of this method are presented based on computer simulation experiments. Diffraction patterns produced by such diffractive optical elements are shown for binary intensity objects described either by the Cartesian coordinates of their non-zero points or by image format files. The method by itself stands as an effective method to calculate phase diffractive elements for free space optical interconnection between an array of point sources and an array of point detectors, but is shown to be also useful to generate binary intensity objects. The optimization of the phase function which describes the phase diffractive element is also demonstrated by means of a micro-genetic algorithm.

The present research work is devoted to the realization of an efficient fiber-waveguide optical coupling between single-mode fiber and rectangular waveguide. The outcomimg laser beam exiting from the fiber has a gaussian transversal field distribution. On the contrary, the single-mode waveguide has an asymmetric transversal field distribution in X and Y-axis. To transform the outcoming circular laser beam onto a rectangular, size adjusted, spot we have used a multilevel diffractive phase element fabricated directly on the top of the fiber by means of nanolitography. The diffractive phase element is calculated to focus and reshape the gaussian symmetric beam exiting a single-mode fiber into a desired asymmetric intensity distribution at the waveguide input plane. Phase modulation is obtained by multilevel profiling a polymeric material coated on the top of the fiber by means of a specific fabrications process including e-beam lithography and chemical etching. Experimental results obtained for fiber-waveguide coupling with a 20 microns diameter diffractive element are also presented.

The paper presents the calculus of efficiencies in diffracted orders of a concave blazed diffraction grating. The diffraction grating was designed with blazed angles and diffraction spacing variable. We have applied the electromagnetic theory in order to obtain the grating efficiency, which is a sum of all diffracted orders efficiencies. We would expect the sum to be equal to unity. Our result show that this sum is greater than 0.94 and less then unity for some incident angles. The calculation of grating efficiency by means of electromagnetic theory was performed numerically. Our calculations did not take into account of the effect of multiple scattering; that is, light which is scattered from one facet to another before leaving the grating. The various diffracted orders were coupled together by a boundary condition on the surface of the grating. We conclude this groove profile of the grating leads to a better efficiency compared to a typical blazed concave grating.

In this paper we compare two techniques to design diffractive gratings with periods close to the wavelength of the illumination beam. The first method, based on the Rayleigh method, is faster and allows good result if grating period is more than 1.2 bigger than the wavelength. The second method, known as Fourier Modal Method, is more precise but also requires a longer calculation time. Results obtained from the computer simulations and experiments are presented for gratings with 0.750μm and 1.5μm period illuminated by a collimated wave with 0.633μm wavelength.

Ray tracing is one of the methods to design diffractive optical elements. We included this theory to obtain two or four Gaussian beans from one Gaussian beam. The power distribution has been calculated by near field diffraction. First we considered one dimensional case and then the two dimensional case. Calculations are numerically solved using a computer program. The solutions for 1:2 branching are resolved for 1:4 branching in one-dimensional and two-dimensional formulations. The basic model for computing is that a given Gaussian beam is equally divided into two or four beams to produce two or four Gaussian beams with same beamwidth as the incident beam.

The second-order coherence (correlation) functions are used to investigate the classicality (nonclassicality) of quantum states, as defined by the existence (nonexistence) of a positive definite (Glauber-Sudarshan) P-representation. We study nonclassical behavior as revealed by sub-Poissonian statistics and/or violation of the classical Cauchy-Schwarz inequality. The two-mode states considered include Bell-like superpositions of Fock states, Schrödinger cat states and the ideal squeezed states.

One of the most promising implementation of artificial neural networks is optoelectronic implementation. Optical interconnections are useful for neural networks as far as one can take advantage of the special potential of 3D connection through free space. In hardware implementations of neural networks, the weights values will be materialized in a technological process during which various errors may occur, so that the resulting network will use more or less deviated weights. This paper studies several aspects concerning the optical interconnection of artificial neurons. The authors analyze the problems involved by using computer-generated holograms (CGH) for these interconnections and some methods of designing such diffractive elements. The authors also analyze the error sources and the consequences caused by random deviations of the neurons interconnection weights from the accurately computed values. The theoretical considerations are illustrated by designing an auto associative memory built for graphic pattern recognition. Neurons interconnections are to be implemented optically by computer generated holograms (CGH). The network functioning was simulated on computer and the paper presents also the results of simulations on a data set and a CGH layout for neuron interconnections.

Diffractive optical elements (DOE’s) can be used to manipulate the amplitude, the phase and the polarization of light beams. They can operate over a wide range of wavelength from UV to x-ray radiation. Interest in DOE’s has grown rapidly in recent years since they are smaller and lower in size and weight than conventional optical elements and in addition allow optical functions impossible to reach with other refractive or reflective optical elements. In this paper we report results obtained in DOE’s design and fabrication at the LILIT Nanolithography beam line developed at the national laboratory TASC-INFM. Among the design methods we have used, the phase retrieval iterative algorithm approach is presented in more detail here. There are also presented aspects involved in the fabrication of high-resolution zone plates for focusing soft x-rays. The fabrication process is based on e-beam lithography and etching techniques similar to those used in the microelectronic technology, allowing structures sized down to few tens of nanometers. Experimental results are presented for some applications of our DOE’s: laser beam shaping, optical tweezers array generation and x-ray microscopy.

In the following rows a limitation device of the incident laser power in an optical system will be described, to prevent the destruction or the spoil of the captor situated in the extremity of the system. This device is based on the second order non-linearity of an inserted medium in the optical system used to obtain a beam geometry modification, for incident powers which exceeds a certain threshold, which will lead to the defocalization of the entire optical system and to the decrease of the incident light power on the captor.

Photonic devices that implement specific integral transforms of optical beams and optical pulses are presented. They include integrated devices, such as semiconductor waveguides with a prescribed refractive index profile, patterned electro-optic materials as reconfigurable waveguides, integrated lenses or nonlinear and dispersive materials for characterization of optical pulses. Set-ups that generate phase space distributions such as the spectrogram or the Wigner distribution function are also presented; they can be integrated into a device if all their components are micromachined. The usefulness of these phase space set-ups for characterizing micro-optical objects is demonstrated by experimental data referring to micro-optical lenses and laser beams.

A method for calculating the transmission of a two-dimensional (2D) photonic crystal (PhC) of finite extent is presented. The 2D PhC is regarded as a collection of identical quasi-1D diffraction gratings stacked in the propagation direction. The dielectric permittivity profile of a grating is arbitrary in general and can be approximated with a staircase, by dividing it in slices. For each slice, a 1D eigenvalue problem is solved, using Fourier expansions and 'fast Fourier factorization' rules. A fixed frequency is considered at a time, and propagation constants are calculated. Wave propagation from one slice to the next one is described by a scattering matrix algorithm that emerges from continuity of field tangential components at interfaces. The method described has the following advantages: dimension of the eigenvalue problem is reduced, convergence is improved, and material dispersion can be taken into account. Results for 2D photonic crystals composed of square and circular shaped rods are shown and discussed.

Spontaneous emission in atomic system arises due to the interaction of atoms with environmental modes. Atomic coherence and quantum interference are the most important mechanisms for controlling the spontaneous emission. We show that under certain conditions complete quenching of spontaneous emission is possible. By using V type three level system driven by two fields, the phase dependence of quantum interference is investigated. The Fano type and P type interference mechanism in atomic coherence system driven by microwaves are investigated. In particular we find that both phase dependence interference mechanism may be destructive simultaneously and thus lead to spontaneous emission cancellation in different parts of the spectrum. One of the most important applications of this system is the refractive index enhancement.

The effect of low amounts of antimony, tin, dysprosium, samarium and manganese on structure and optical properties of chalcogenide glassy semiconductors As₂S₃ and As₂Se₃ is investigated. The fundamental absorption edge shifts to longer wavelength with doping; the largest shift was observed for doped chalcogenide glasses. Near the edge absorption the impurity affects strongly the slope and the magnitude of the weak absorption tail. The steady-state and transient photoconductivity characteristics are adequately interpreted in frame of the model, in which transport and recombination of non-equilibrium holes are controlled by exponentially distributed hole traps with the distribution parameter T*, depending on the glass composition. Some application of amorphous chalcogenide thin film structures as registration media are presented.

Commercial available red and infrared diode lasers have been tested. A set of ten pieces of red 25 mW nominal output power and five pieces of 0.5 W infrared diode lasers have been investigated. The laser output power has been measured by using an Ophyr power-meter. Ophyr F150 head (3mW noise) was used for power measurements of the infrared diode laser and Ophyr 3A-IS integrated sphere was used in the case of red diode lasers. A Spiricon laser beam analyzer was used to determine the beam intensity distribution. An API wave-check wavelength meter measures the wavelength of the diode lasers. Temporal behavior of the diode lasers over periods of days was recorded. The influence of ambiental conditions is considered. Our study guarantees the proper choice of the diode laser to be used in specific applications such as medical, and industrial applications.

In this paper we present a glycerin-filled interferometer which is suited to determine the thermally induced space-time refractive index profile of an optical, uranyl-ion-doped glass. The refractive index of the sample changes when irradiated with an Ar⁺ laser or a pulsed Nd-YAG laser and modifies the interference pattern of a probe beam. According to the task performed, the interferometer is used in longitudinal and transversal configurations. Using the model of the thermal absorption and diffusion, one can find the relation between the refractive index variation, temperature gradient and phase shift of the interference pattern. We calculate the refractive index changes of the on and off axis as well as its temporal variation during the relaxation process. The modifications of a thermally induced phase grating is interpreted in terms of a one-dimensional, structured gaussian beam obtained from a double refractive crystal of KDP (KH₂PO₃).

In this paper we report theoretical and experimental results concerning the realization of the phase-matching conditions for the internal second-harmonic generation in InGaAs quantum-well laser diodes emitting around 980 nm in order to enhance the conversion efficiency. The role of the phase-mismatching in the spectral distribution of the internal second-harmonic generation in the CW operation of the above-mentioned lasers is also analyzed. The emission of pairs of narrow blue-green peaks having perfectly symmetrical spectral positions with respect to the central peak of pure second-harmonic generation at ~ 480 nm is most probably enhanced by a mechanism of reciprocal cancellation of the respective phase-mismatch vectors. The theoretical results obtained by numerical integration of the coupled amplitude equations corresponding to the fundamental and second harmonic concerning the interaction length and generation efficiency are in good agreement with the experimental data. The obtained results are important for the assessment of the relationship between the structural parameters of the laser and the conditions which contribute to the stimulation of second-order optical nonlinearities in the laser active region.

Method of using the matrix method optics of light-scattering media for research the polarization characteristics of objects with dynamically varying geometrical optic parameters is described in this work. The results of measuring the Mueller matrix components of nematic liquid crystal (NLC) during the activity of electrical impulse are given. The character of transformation matrix (MT) and light scattering matrix (LSM) symmetry of exploring medium is determined. General analysis of nonzero components time dependencies of NLC Mueller matrix is given. The possibility of using the electro controllable liquid crystal as the model object for exploring the influence of the shape, size and orientation of nonspherical particles on the size of their Mueller matrix components is noted.

In this paper we analyze the electromagnetic modes in photonic crystals. This is important because of the wide range of potential applications of structures which allow a complete control over light propagating in them. We focus to study the fundamental behavior of one- and two-dimensional photonic crystals, which are easier to investigate than three-dimensional structures. We will study the photonic band structure in the TM modes (E-polarization) and in the TE modes (H-polarization).

There is presented a simple method to obtain the pumping temperature T_p for EDFA. We propose the analytical method to obtain the pumping temperature for EDFA (Erbium Doped Fiber Amplifier). We have obtained the pumping temperature of EDFA by varying the voltage parameter V_TEMP in the following interval V_TEMP ε (0 ÷ 2.5). With these sets of values we calculated the pumping temperature T_p of the EDFA as a function of V_TEMP.

Nanocrystalline silicon is studied with a view to obtaining a new photonic material. Non-equilibrium electronic processes in such materials play a significant role. We have studied trapping phenomena in nanocrystalline porous silicon and nanocrystalline silicon-based Multi-Quantum Wells structures by means of Optical Charging Spectroscopy method, which is a very good and sensitive method. We have also analyzed the modeling of the processes that occur during our measurements. This modeling allows us to separate the relative contribution of the different types of discharge currents that can appear: ohmic conduction currents of either equilibrium or non-equilibrium carriers, displacement currents, diffusion currents and tunneling currents through insulating layers (in Multi-Quantum Wells structures). It also allows us to increase the accuracy of the determination of the experimental trap parameters and to determine parameters that are not directly measurable. The model can be applied to other nanocrystalline semiconductors and can be easily generalized for other high resistivity materials.

The results of steady state and transient photoconductivity characteristics of As-S-Sb thermally deposited amorphous thin films are presented. The lux-ampere characteristics of the steady-state photoconductivity are described by the power low dependence σ = B • F^γ with the power index [equation] where T* is the parameter of localized states distribution. The spectral characteristics of the photoconductivity for As-S-Sb thin films represents a curve with a broad peak centered at 2.50-1.93 eV, and is shifted in the low energy region of the spectrum when the Sb content is increasing in the glass alloy. The transient characteristics of As-S-Sb amorphous films are discussed in frame of trap-controlled model for an exponential distribution of localized states in the band gap of amorphous semiconductor.

Raman spectroscopy which provides valuable information on the structural parameters of QDs was used for monitoring of the lateral oxidation of InAs/AlAs QD structures and study of the phonon properties of InAs QDs in aluminium oxide matrix. Optical phonons of InAs QDs were found to be affected by both strain and confinement. Raman spectra measured from non-oxidized area reveal asymmetric lineshape of LO phonons in InAs QDs and demonstrate its low-frequency shift with increasing excitation energy that is explained by QD size distribution and phonon confinement in smaller-size dots. Raman spectra taken from oxidized area show an increase of the LO peak intensity and the shift of the phonon line position towards higher frequency. The first effect is explained by formation of wide bandgap aluminium oxide matrix that leads to the shift of confined electronic states in InAs QDs closer to the resonance with the laser excitation energy. The latter is caused by increasing mechanical strain in InAs QDs due to a shrinkage of the aluminium oxide layers. At the boundaries of oxidized/non-oxidized areas the presence of amorphous and crystalline As clusters is evident.

The fabrication process of c-Si waveguides based on the anisotropic etching of Si<111> oriented wafers is described. To obtain c-Si waveguides, the anisotropic etching was combined with an isotropic pre-etch step to a depth equal to the thickness of the final c-Si freestanding structure, followed by side-wall passivation. In addition, a second pre-etching step was performed to establish the depth of the air gap that acts as the bottom cladding of the waveguide. Freestanding c-Si waveguides with very smooth surfaces were obtained by anisotropic etching in a KOH solution. By using a Si₃N₄/SiO₂ mask layer, double waveguides were obtained. The possible applications of c-Si based free standing structures include devices for optical communications and evanescent-wave bio- or chemical sensors.

The objective of this paper is to research some technological aspects concerning with the execution of the dividing (incremental) disk, which is a component part of the incremental rotating transducers. The performed investigations deal with the manufacturing process by material addition, using the selective vacuum evaporation of thin metal films through a contact metallic mask. There are presented the technological stages of execution of the masks, realized as incremental metallic disks of small sizes. The shadow effect causes the non-uniformity of thickness of the films in the mask gaps. In this regard, the authors present a mathematical model for the film profile evaluation in the case of planetary system evaporation using an electron gun as vapor source.

The present technical and technological developments determined the apparition of the mechatronic systems as heterogeneous and complex systems that perform complex goal oriented functions. These systems are the result of the synergistic integration of many disciplinary homogeneous systems, basically the mechanical, electronic and software ones. In these conditions, the paper will present the synergistic definition of the mechatronic systems, the aspects regarding the synergistic integration of the optical system in the mechatronic context and the resulted concept of mechaoptronics. According to these concepts, the reliability problem of the optical systems integrated in a mechatronic context will be developed at both the functional and structural levels together with the corresponding reliability analysis framework.

This paper presents the new technologies those were applied in manufacturing of lighting systems of road vehicles. Litronic gets an important role in the front lighting of new cars. New perspectives were opened by PES - reflectors and FT technology. It is also very interesting the application of Power LEDs in car lighting systems.

Pulsed laser deposition (PLD) is widely used to prepare various kinds of thin films. From many experimental results the film surface has been found to be strongly affected by so-called droplets, which are relatively large target material particles in solid or liquid state carried with the plume. In order to satisfy both purposes of high deposition rate and good quality by the PLD, we have investigated the plume reflection process from the viewpoint to avoid the big particles deposited on the substrate. In the present paper we investigate the influences of the system parameters on surface thin film quality and the deposition rate. Some optimization proposals are also included for this deposition technique.

In order to obtain specific channels and reservoirs in glass for analytic systems, the structuring of borosilicate glass has been studied. We used wet etching in HF diluted solution for etching channels up to 150 μm depth. A mask obtained by successively wet etching of previously evaporated Au and Cr layers has been used. A thick SJR 5740 type resist has been spun-on in order to accomplish the optical transfer of the pattern. A normal underetching not larger than the depth, has been obtained when adding a small amount of nitric acid, and using an appropriate annealing process after metal deposition. Neither pinholes nor cracks have been noticed after getting an etching depth of 180 μm. Double side etching has been performed for penetrating the glass. The dependence of the etching rate vs. both HF and HNO₃ concentration is outlined together with the etched surface quality.

Laser induced surface cleaning is the adequate method in a large variety of industrial domains as microelectronics, optics, photonics. By comparison to chemical and/or mechanical cleaning, laser cleaning has the advantage of a very good selectivity on the surface and in depth of the material, no surface contamination, without stress in the material volume and environmental safe. It seems that laser cleaning can be developed in a method to be currently used in microelectronic industry. For an efficient laser cleaning of metallic thin films without damage of the silicon wafer, a careful optimization of the incident laser energy, fluence, intensity and number of laser pulses is needed. We have developed an analytical procedure to study the temperature fields in pulsed laser heated solids, for a deeper knowledge of the laser-thin film substrate interaction.

The interaction of solids with multiple electromagnetic fields is of great importance in quantum electronics. In this paper the behavior of the heat transfer in a solid irradiated by multiple laser beams is investigated. The directions of laser beams propagation are supposed to be along Cartesian coordinate axes. The spatial distribution of laser beams is supposed to be Gaussian. The model is valid for any laser-solid system whose interaction can be described by the Beer law. Calculations are performed using the integral transform method^1,2. The spatial and temporal temperature field distributions are plotted considering a real situation in which ZnSe samples are continuously irradiated with one, respectively three CO₂ laser beams.

We present theoretical results in modeling ionic inter-diffusion in optical glasses. Several interface phenomena are studied and their influence on the shape and the position of the waveguides is explained. The most important process is re-diffusion. We investigate the influence of the maximum surface concentration, of the clustering and of the time constant for reaching interface equilibrium. Their influence is taken into account by introducing supplementary terms in the inter-diffusion equation or by modifying boundary and initial conditions. All the parameters of the final buried guides depend on surface phenomena. The total amount of ions in the guide, the width at half the maximum, the burying depth and the shape of the profiles depend on surface processes. The influence appears for the mono-mode, as well as for multi-mode structures.

Modern electronic system design is based on integrating heterogeneous components (μP, DSP, ASIC, memories, buses, MEMS, MOEMS, etc.) on a single chip. These highly integrated systems are commonly known as System-on-Chip (SoC). System validation by HW-SW co-simulation can enhance the quality of a System-on-Chip (SoC) design. In this paper, we present a SW simulation model for both operating system and application. The model gives fast simulation exploiting the native execution of OS and application SW. For accurate simulation, it enables timing simulation with several levels of timing delay granularities, which enables the designer to have trade-off between simulation speed and accuracy. For timing delay estimation, the OS and application SW codes are compiled for a target processor and the delay of each assembly instruction is calculated. Then, according to the granularity of timing delay chosen by the designer, delays are annotated into the OS and application SW codes. For HW-SW co-simulation of the entire SoC, the execution of proposed model, we present a bus functional model (BFM). The BFM exchanges simulation events between HW and SW simulation while synchronizing their timing simulation. The technique proposed in this paper could be useful for complex heterogeneous system validation and design.

An interesting alternative to the former use of HEBS glass (suitable e-beam exposed to give a “true” variable transmission contact mask) is the “simulated” variable transmission gray-tone projection reticle. It is simply obtained from a film generated on a 4000 dpi laser writer and then 10x reduced on a Cr.-glass plate. This projection gray-tone reticle, having sub-resolution pixel elements, is able to modulate light intensity in a thick positive resist to give arbitrary 3-D shapes. A tremendous enhancement in resolution, both for horizontal and vertical direction, was obtained by applying an original combination of binary masking technique (N powered by M levels for M reticles having each N gray-tones) with a proper focusing depth of the projection objective (just at the middle of the exposed resist layer). So, it was possible to structure a thick resist in very complex smooth 3-D shapes, which are very useful for micro-optics, by using M exposing steps. Interesting applications for micro-optics are given.

Many industrial applications (optical devices, micro/nanotechnology, etc.) require the development of advanced positioning systems. They should have submicronic resolution, often in a practically unlimited working range, as well to be stable, reliable and to have compact construction. By use of piezoelectric materials, devices having the potential to control the system structure and consequently the degrees of freedom of the mechanical components could be achieved. The paper presents some of the actuators, built and experimentally tested by the authors, as well as their associated mathematical models.

The development of MEMS microsystems can be increased by integration of optically active parts. Micromachining techniques allow the fabrication of monolithically integrated Fabry-Perot microcavities, avoiding hybrid assembly technique, which is a combination of etching and wafer bonding. These microcavities can be used as sensors, as modulators or as tunable optical filters. We investigated different mirror materials: silicon nitride and polysilicon and different sacrificial layers: polysilicon and phosphorus doped silicon dioxide (PSG), using LPCVD and CVD techniques. Different arrays and shapes for the top mirror, which is movable, were analyzed in order to establish a structural material with low tensile stress. The optical constants were determined by spectrophotometric methods. Experimental data and simulations were compared.

The silicate spin-on-glass (SOG) assisted low temperature bonding of different types of glasses on silicon and silicon compounds substrates is widely used in micromachining of analytical devices. Two silicate spin-on glasses (SOG), potassium silicate KASIL 2130 and sodium silicate N/N CLEAR, both of them from PQ Inc., are used. Previous experiments have revealed the formation of clusters and voids in the cured glass layer, that diminishes the bonding quality. A quantitatively analysis of the bonding process in terms of work of adhesion and interfacial tensions enabled us to identify the hot points of the bonding process: the wettability of the surfaces to be bonded, the appropriate concentration of the soluble glass, the adhesion of the spin-on-glass on these surfaces in both liquid and solid state, the spun-on-glass curing process. To overcome these hot points appropriate technological steps are added to the bonding process: O₂ plasma and hot HNO₃ exposure of glass/silicon respectively silicon nitride surfaces, one minute delay of spinning after sog-deposition on the substrate, increasing up to 125°C the annealing temperature of the spun-on-glass. Smooth, uniform, reproducible glass layers, are obtained and the dependency of their thickness (ranging from 100 Å to 5000 Å) versus silicate concentration of the soluble glass is determined. In order to explain the clusters and voids formation, successively observations of the cured layer after the annealing treatment and after room temperature storage are performed, and show that room temperature storage of non-completely cured silicate layers leads to the formation of clusters. The effect of the concentration of the soluble silicates is qualitatively analyzed, by means of optical microscopy, showing that silicate solutions having 2-3% of wt. are suitable for bonding applications with best results when the obtained glass layer is thin enough.

The dynamic behavior of three section DFB self-pulsating lasers, used as clock recovery device, is theoretically analyzed using a time domain traveling wave simulator. The effect of the bias operating conditions on the self-pulsation frequency is discussed through both static and dynamic analysis. Detailed results on the clock recovery dynamics and the jitter characteristics are presented injecting a realistic pseudo-random data stream.

Computer simulation is carried out to investigate the impact of Cross-Phase Modulation (XPM) on the Bit Error Rate performance of a single segment and multi-segment periodically amplified Wavelength Division Multiplexing (WDM) Intensity Modulation with Direct Detection (IM/DD) transmission system at a bit rate of 10Gb/s with Standard Single Mode Fiber (SSMF). A simple two channel WDM transmission system, one is effected channel under investigation known as probe channel and the other is the interfering channel known as pump channel are co-propagating inside the SSMF. The results show that XPM induced eye penalty increases with the increase of pump channel power and decreases with the increase of channel spacing between probe and pump channel. For 5dB penalty, the maximum allowable pump channel power is found to be 6dBm and 8dBm, for multi-segment and single segment WDM system respectively. For 3.5dB penalty, the minimum channel spacing is found to be 60GHz and 100GHz for multi-segment and single segment WDM system respectively. Multi-segment periodically amplified configuration can be used to reduce the XPM induced eye penalty for WDM system that requires a high probe power, low probe power and high channel spacing.

In this paper the authors present some characteristics of the human visual receptor showing that it is a perfect model and a source of technical solutions. Hence, the human eye is very close by the individual reception of photons, attenuating unfavorable consequences of diffraction from the ulterior processing of image at the retina’s level, and through the multiple coincidences method it filters the noise, etc. Thus, the authors present the models of neuronal networks which exist in retinas, the models realized in the optoelectronical technology, with the helping of the directional couplers.

This paper reviews recent progress in ultrashort pulse generation with mode-locked fiber lasers utilizing semiconductor saturable absorbers to initiate the mode-locking mechanism and to stabilize the laser pulse train. The saturable absorbers were monolithically grown by molecular beam epitaxy on top of a Burstein-Moss shift Ga_0.47In_0.53As/InP distributed Bragg reflector. The design guidelines and the main features of the semiconductor saturable absorber mirrors are summarized. Synchronization of a harmonically mode-locked pulse train to an external signal and repetition rate stabilization is demonstrated by directly modulating the 980 nm pump diode laser used both to provide gain and to optically modulate a semiconductor saturable absorber mirror.

The paper presents a practical method for fabricating wavelength-selective fused-type couplers. The detailed procedure is described, which allows for reliable fabrication of coupler with arbitrary parameters of wavelength channels. The simple model for the single-mode fused tapered coupler was used to validate the method and to define the technological limits.

The paper deals with the description of a simulation procedure for the design and the optimization of tunable multi-section distributed Bragg reflector (DBR) lasers. In particular a special attention is dedicated to the design of two-section DBR lasers with operating wavelengths matching the ITU frequency standard grid only by grating current tuning. To our knowledge this is the first time that by a proper design procedure this condition has been satisfied.

The decoder, an important element of electronic circuits with microprocessors can be implemented also in the integrated optoelectronic technology. In this paper, the authors present from theoretical point of view, the realization of directional couplers based on decodors.

An optical transport network based on dense wavelength - division multiplexing DWDM technology is the next logical step in the evolution of Internet network. An Optical Internet network is defined as any Internet network where the network link layer connections are “dedicated” wavelengths on a Wave Division Multiplexed optical fibre directly connected to a high performance network router. The high performance network router replaces traditional ATM and SONET/SDH switching and multiplexing equipment, the essential statistical multiplexing device that controls wavelength access, switching, routing and protection. The optical amplifier is the key element that contributes to design an Optical Internet network. The design of an optical component and in particular an optical amplifier can directly and significantly affect the performance of an optical system. With the help of PTDS toll I will demonstrate the advantage of using L - band amplifiers especially for long - haul terrestrial or submarine DWDM systems in which thousands of amplifiers might be needed in a single transmission link. This is due to the exceptional feature that permits in a cascade configuration a very flat gain. It is demonstrated that L -band amplifier doesn’t require a gain-flattening fiber (GFF) compared to C -band amplifiers.

Transmission of 80x40 Gbit/s channels has been simulated over straight-line 400 km NDSF with 100 GHz spacing and record 90-and-120 km amplifier spacing. The amplifier and fibre modules are designed for wide-band simulation and include file - input wavelength - dependent characteristics. All the simulations were done base on a very powerful software simulator tool - PDTS - produced by Virtual Photonics.

The taper (i.e. thin fiber with transitions from large to small diameter) is created during pulling of the molten fiber. Its shape depends on many parameters of the pulling process, such as pulling speed, pulling temperature, pulling stages step, etc. This paper attempts to describe the taper shape as a function of pulling parameters and provide comparison for different heating methods.

The realization of a portable laser rangefinder, capable to measure ranges up to 1,200 m, raises particularly difficult problems related to the selection of an appropriate laser diode, having a sufficient optical power, but also the generation of very short rangefinding pulses, with very steep fronts. The authors used as emitter a high power pulsed laser diode CVD 193 from Laser Diode Inc. and build up for it a driving stage made up of a signal formatter that takes over the pulse sent by a microcontroller (that controls the whole rangefinder) and a switch based on a power high frequency MOSFET transistor 501N16A from DEI.

The realization of a portable laser rangefinder, capable to measure ranges up to 1,200 m, raises some difficult problems. The first one is that a good temporal resolution is required to get a good ranging resolution and that means that both the transmitter and the receiver must be rapid. The other problem is that at measurements of range larger than 1,000 m the level of the reflected pulse current in the phodiode is of the order of the dark current, which has to be compensated, as well as the temperature offset of the photodiode (in order to keep the calibration). A novel solution was adopted to solve these problems: the AC coupling (it doesn’t matter any more the dark current nor the temperature offset) and the use of wide band amplifiers, with a very low noise.

A portable laser rangefinder, capable to measure ranges up to 1,200 m, implies the measurement of time intervals ranging between some tens of ns and some tens of μs with an accuracy of less than 1 ns. Taking into account that laser pulse rate is low (1...10 kHz) our solution was the time expansion in few stages followed by a classical time interval measurement. We actually expanded the time range 100 ns ÷ 10 μs into the range 25 μs ÷ 2.5 ms and the new time interval is measured using a 5 MHz quartz driven clock. The measurement accuracy is then 0.42 ns.

In this paper we report original results related to the degradation of laser diodes parameters, as they are subjected to electron-beam and gamma-ray irradiation. For this purpose, we investigated two double heterostructures laser diodes, operating at 808 nm, 850 nm respectively. The maximum emitted optical power was in the range of 5 -6 mW, in CW operation mode. Radiation induced modifications of laser diodes electrical, optoelectrinc and optical parameters were studied. Simultaneously, the responsivity of the embedded photodiode was monitored. Slightly changes in the laser threshold current, emitted radiation wavelength, serial resistance and external quantum efficiency were observed, while more important variations of the photodiode responsivity and laser diode spectral distribution were noticed. The temperature dependence of device parameters after the irradiation was also studied. The work under way is performed in the frame of EU’s Fusion Programme.

The characteristics of laser diodes (wavelength of the emitted radiation, output optical power, embedded photodiode photocurrent, threshold current, serial resistance, external quantum efficiency) are strongly influenced by their driving circumstances (forward current, case temperature). In order to handle such a complex investigation in an efficient and objective manner, the operation of several instruments (a laser diode driver, a temperature controller, a wavelength meter, a power meter, and a laser beam analyzer) is synchronously controlled by a PC, through serial and GPIB communication. For each equipment, instruments drivers were designed using the industry standards graphical programming environment - LabVIEW from National Instruments. All the developed virtual instruments operate under the supervision of a managing virtual instrument, which sets the driving parameters for each unit under test. The manager virtual instrument scans as appropriate the driving current and case temperature values for the selected laser diode. The software enables data saving in Excel compatible files. In this way, sets of curves can be produced according to the testing cycle needs.

In this paper we build a statistical model for the LIDAR signal validation (estimation, selection, statistical validation of the Mie backscattered optical field from pollutants at medium and long range distances). The LIDAR backscattered optical signal is realized via the operative characteristic. Defining Q_o as the false alarm probability and Q_d the detection probability, the operative characteristic is a curve in the plane defined by the indecision zone of the LIDAR signal validation. The aim of this paper is to propose some optimization methods of the operative characteristic associated with the LIDAR signal validation.

In this work a few configurations of waveguide reflective modulators are studied theoretically. The waveguides considered here are made from epitaxial silicon layer grown on heavy doped silicon substrate. The working wavelength is 1.3 µm. The optimal configuration of the proposed devices was obtained using the optical analysis.

The communication networks, highly specialized, were developed according to the type of transmitted information (vocal signal, data bases, TV signals). Presently, the networks’ evolution is targeted towards high velocities and services integration, networks characterized by SONET/SDH standards. SDH (Synchronous Digital Hierarchy) is the first standard, which provides an integrated system of network management and maintenance, ensures a uniform and global hierarchy of multiplexing and has advantages concerning the configuration of external network types. In this paper is described an access network for voice and dates communications, on optic fiber, built up with LOGES 2M Alcatel access routes (2 Mbps access) and with SDH transmission systems type Alcatel 1641SM (155Mbps).

One of the most critical components of a PSK receiver is the PLL. A technique that makes possible to avoid a PLL device is based on the transmission of a reference carrier together with the modulated signal. The carrier can be extracted at the receiver end for demodulation. In this paper is made an analysis from the point of view of the performances of this kind of system and the main purpose is to minimize the error probability searching a suitable power splitting ratio at the transmitter.

The color TV is an eloquent example of the applied bionics. The knowledge of the human visual analyzer’s characteristics allows the elaboration of the color TV systems. In this paper the authors describe the principles of the color television based also on the applied bionics, but for this, the optical image isn’t transformed in the electrical signals, it remains as the optical signal from reception to view including the transmission channel.

This paper is concerned with the concept study of an alarm system with infrared remote control operability: we propose such a system which assures in good condition the security of the protected property.

The paper presents both conceptual and computational features of quantum transport in semiconductor nanostructures. The results comprise microelectronic structures (MOSFETs, heterojunction devices) where the quantum effects count as well as nanometer-sized semiconductor structures.

The completion of the DNA sequence of several genomes, including the human one, has opened completely new scientific and technological frontiers. The huge amount of genetic information available requires the development of faster and cheaper analytical tools. This can be possible by miniaturising the analytical system itself and by the development of proper analytical procedures, involving fluidic processes. A precise genetic identifying technique is hybridization, that can be accomplished in an array format on very small bidimensional surfaces. In order to automate the fluidic process involved in the DNA hybridization, three micromachining techniques are approached by the authors team, for obtaining reservoirs with volumes ranging from 1nl to 2μl using different materials as polyimide, silicon and glass. Several configurations were proposed targeting a turbulence free fluid flow. A qualitatively fluid flow study was performed and the influence of the reservoir shape was revealed. One obtained device was tested in a Laser Induced Fluorescence detection set-up.