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In this manuscript, the structural, opto-electronic, and thermodynamic properties of Zn[Al.sub.2][Se.sub.4] chalcogenide compounds were studied in detail using the full potential linearized augmented plane wave method. The exchange and correlation potentials used in density functional theory were calculated using local density approximation, the generalized gradient approximation (GGA) method, and the modified Becke-Johnson (mBJ) potential using Wien2k code. The obtained results were compared with each other as well as with available experimental data. At ambient conditions, Zn[Al.sub.2][Se.sub.4] is a direct wide bandgap ([GAMMA]-[GAMMA]) semiconductor with a bandgap of 2.1 and 3.3 eV with GGA and mBJ potentials, respectively. Density of states (DOS; total DOS and Partial Density Of States (PDOS)) and electron density contour plots were in similar accordance with bandgap, showing semiconductive behavior and covalent bonding nature. The optical properties like the real and imaginary parts of the dielectric constant, the energy loss function L([omega]), and the conductivity [sigma]([omega]) were calculated. Optical aspects show interaction among phonon and electron in terms of long-range and short-range forces. The studied compound is very useful for various linear-nonlinear optical devices, so this compound is very valuable for several linear-nonlinear optical devices. So this manuscript represents a comprehensive approach for calculating the complete set of useful properties of the Zn[Al.sub.2][Se.sub.4] compound, which can provide support for understanding various device phenomena such as electrochemical sensing, photovoltaics, and nonvolatile electronic memories. Keywords: chalcogenide compounds, first-principles study, opto-electronic property, modified Becke-Johnson (mBJ) potential, 1. Introduction The majority of the growing problems can be handled by using leading renewable energy resources like solar energy. Nowadays, considerable ongoing research is dedicated to ternary semiconductors [A.sup.II][B.sub.2.sup.III][C.sub.4.sup.VI] [...]

We demonstrate here the layer-by-layer (LbL) self-assembly of conducting [[poly(styrene sulfonate)-poly(vinyl alcohol)/polypyrrole].sub.n] [[(PSS-PVA/PPy).sub.n]] multilayer film with interesting electrical and photoelectric features. Increments in sheet conductivity and photoelectric response with increasing bilayer number are pioneerly recorded. The fantastic phenomenon is determined as the accumulative electrons tunneled across insulating PSS from bottom to top PPy chains. The resulting multilayer films give a linear growth in bulk conductivity and maximum photocurrent density. Careful examination of data and characterizations indicates that the fantastic effects in electrical conduction and photocurrent are accumulative electrons tunneled across PSS from bottom to top PPy., INTRODUCTION Layer-by-layer (LbL) assembly has an ability to fine-tune the composition of nanostructured films, which are preferred in modern nanoscience and nanotechnology [1-6]. The merits of LbL assembly technique on [...]

We investigated the electrical properties of the In-Ga-Zn-O (IGZO) film under light illumination. We measured the photoconductivity of a-IGZO thin film under light illumination with various intensities. We extracted the photoexcitation activation energy and dark relaxation activation energy through extended stretched exponential analysis. Dark relaxation characteristics, which are related to the recombination process, show longer time constant, τ, larger effective activation energy [E.sub.ac], and lower stretching exponent, β, with wider activation energy bandwidth, [Δ.sub.ac], than those corresponding to those of photoexcitation. These indicate that recombination takes place more slowly and through more deeply bound activation processes with the broader distribution of activation energies than those corresponding to photogeneration process. The wider distribution for the dark relaxation energy for the higher light intensity suggests that the metastable state distribution is related to the distribution of the oxygen vacancy state, [V.sub.o]. We also concluded that the usage of the right value of the attempt-to-escape frequency is important to estimate the exact value of [E.sub.ac]. PACS Nos.: 73.50.Pz, 73.50.-h, 73.61.-r. Nous etudions les proprietes electriques de films de In-Ga-Zn-O (IGZO) sous eclairage lumineux. Nous mesurons la photoconductivite de films minces de a-IGZO sous illumination d'intensite variable. L'analyse etendue par exponentielle etiree nous permet d'extraire l'energie d'excitation d'activation et l'energie de relaxation d'activation en obscurite. Les caracteristiques de relaxation en obscurite, qui sont reliees au mecanisme de recombinaison, montrent une plus grande constante de temps, τ, de plus grandes energies d'activation efficaces, [E.sub.ac], et de plus faibles exposants d'etirement, β, avec une plus large largeur de bande d'energie d'activation, [Δ.sub.ac], que celles correspondant a la photo-excitation. Elles indiquent que la recombinaison se produit plus lentement et via un processus d'activation plus profondement lies avec de plus larges distributions d'energies d'activation que celles correspondant au procede de photo-generation. Ajoutons que la plus large distribution de l'energie de relaxation en obscurite pour des intensites lumineuses plus elevees, suggere que la distribution d'etats metastables est reliee a la distribution de l'etat [V.sub.o] lacunaire d'oxygene. Nous concluons aussi que l'utilisation de la bonne valeur de la frequence des essais-de-fuite est importante pour calculer la bonne valeur de [E.sub.ac]. [Traduit par la Redaction], 1. Introduction Nowadays, amorphous In-Ga-Zn-O thin film transistors (a-IGZO TFTs) are getting a lot of attention from many researchers [1-4]. Compared to other devices, such as a hydrogenated amorphous silicon [...]

In this work, rutile-phase Ti[O.sub.2] particles (r-Ti[O.sub.2], about 360 nm in size) are embedded within a silicon oxide matrix using different concentration ratios of r-Ti[O.sub.2] with respect to Si[O.sub.2]:[H.sub.2]O, so that suspensions of mixed Ti[O.sub.2]:Si[O.sub.2] oxides were obtained and analyzed. These Ti[O.sub.2]:Si[O.sub.2] suspensions were deposited on previously-cleaned crystalline silicon and quartz substrates so that thin films of Ti[O.sub.2]:Si[O.sub.2] were obtained. All films were then exposed to relatively high-temperature thermal treatments in nitrogen and different characterization techniques were used to determine their physical and electrical properties before and after ultraviolet (UV) irradiation. Before high thermal treatment, X-ray diffraction patterns show that the main diffraction peaks for the obtained Ti[O.sub.2]:Si[O.sub.2] films correspond to the crystalline phase of rutile-Ti[O.sub.2]. Infrared analyses before and after thermal treatment show significant changes in the chemical bonding of the final films relative to the temperatures used during annealing. Also, UV-visible spectra provide a constant optical band gap for the films, independent of different Ti[O.sub.2] concentrations as expected. On the other hand, atomic-force microscopy measurements before and after UV irradiation show an appreciable difference in the grain size and surface morphology of the resulting Ti[O.sub.2]:Si[O.sub.2] oxides annealed at 1000 °C. Finally, photoelectrical I-V properties were obtained for all Ti[O.sub.2]:Si[O.sub.2] films by depositing ultrathin titanium stripes on top of the photoactive material and then, measuring the total current flowing through the metal electrode before and after UV irradiation. From these last measurements, a detectable increase in the I-V slope (lower resistance of the titanium stripe) is found for all samples during UV exposure, thus making this device to act as a simple photoresistor based on r-Ti[O.sub.2] particles. PACS Nos.: 78.67.Bf, 73.50.Pz, 61.80.Ba. Des particules de Ti[O.sub.2] en phase rutile (r-Ti[O.sub.2], environ 360 nm) sont ici implantees dans une matrice d'oxyde de silicium, utilisant differentes concentration de r-Ti[O.sub.2] relativement au Si[O.sub.2] : [H.sub.2]O, de facon a pouvoir obtenir et analyser differentes suspensions de Ti[O.sub.2] : Si[O.sub.2]. Ces suspensions sont deposees en films minces de Ti[O.sub.2] : Si[O.sub.2] sur des substrats de silicium cristallin et de quartz prealablement nettoyes. Tous les films sont recuits a relativement haute temperature dans une atmosphere d'azote et nous utilisons differentes techniques pour caracteriser leurs proprietes physiques et electriques avant et apres leur irradiation aux ultraviolet (UV). Avant le traitement thermique, les patrons de diffraction X indiquent que les principaux pics de diffraction des films de Ti[O.sub.2] : Si[O.sub.2] correspondent a la phase cristalline de r-Ti[O.sub.2]. L'analyse infrarouge avant et apres le traitement thermique montre des changements significatifs dans le lien chimique des films finaux selon les temperatures utilisees pour le recuit. De plus, la spectroscopie UV-visible indique un gap optique constant pour les films, independamment de la concentration en Ti[O.sub.2], tel qu'attendu. D'un autre cote, la microscopie a force atomique avant et apres l'irradiation UV montre une difference appreciable de la grosseur du grain et de la morphologie de surface des oxydes resultants Ti[O.sub.2] : Si[O.sub.2] soumis a un recuit a 1000°C. Finalement, nous determinons les proprietes photoelectriques I-V de tous les films de Ti[O.sub.2] : Si[O.sub.2], en deposant sur le materiau photo-actif une ultra-mince languette de titane et en mesurant le courant total dans cette electrode metallique avant et apres l'irradiation aux UV. De ces mesures, nous trouvons une augmentation detectable dans la pente I-V (plus basse resistance de la languette de Ti) pour tous les echantillons durant l'exposition aux UV, determinant ainsi que ce dispositif est une simple photoresistance basee sur les particules de r-Ti[O.sub.2]. [Traduit par la Redaction], 1. Introduction Since the 1920s, titanium dioxide (Ti[O.sub.2]) has been produced commercially for applications in paints, sunscreens, toothpaste, pigments, etc., but it was not until 1972 that Fujishima and Honda [...]

The crystallization of hydrogenated amorphous silicon films with femtosecond laser pulses is one of the promising ways to produce nanocrystalline silicon for photovoltaics. The structure of laser treated films and their hydrogen content are the most important factors for determining the photoelectric properties of materials. In this work we investigated the effect of femtosecond laser irradiation of a-Si:H films with different fluences on crystalline volume fraction, hydrogen concentration, and photoelectric properties of this material. Our results point out that hydrogen out-diffusion accompanies the crystallization process. The increase of hydrogen concentration in the initial a-Si:H films structure affects the kinetics of the crystallization process, but does not lead to a substantial increase of hydrogen concentration remaining in the film after the treatment. The deficiency of hydrogen in the films' structure results in degradation of their photoconductivity, thus other strategies of a-Si:H laser crystallization or postprocessing should be found to obtain device-quality films using ultrafast laser processing. PACS Nos.: 71.23.Cq, 73.50.Pz, 79.20.Ds. La cristallisation par impulsion laser femto-seconde de films de silicium amorphe hydrogene est l'un des moyens prometteurs pour produire du silicium nanocristallin pour utilisation photovoltaique. La structure des films traites par laser et leur contenu en hydrogene sont les facteurs les plus importants qui determinent les proprietes photoelectriques du materiau. Nous etudions ici les relations de l'irradiation laser femto-seconde sur des films de a- Si:H, avec differents intensites sur la fraction cristalline en volume, la concentration en hydrogene et les proprietes photoelectriques du materiau. Nos resultats suggerent qu'une perte d'hydrogene par diffusion accompagne le mecanisme de cristallisation. L'augmentation de la concentration initiale d'hydrogene dans les films de a-Si:H affecte la cinetique de la cristallisation, mais ne mene pas a une augmentation significative de la concentration d'H dans le film apres traitement. Le manque d'hydrogene dans les films degrade leurs proprietes photoelectriques. Ainsi, on doit trouver d'autres strategies de cristallisation de a-Si:H par laser ou un post-traitement, afin d'obtenir des films de qualite par irradiation laser ultra-rapide. [Traduit par la Redaction], Introduction In the last few decades, films of nanocrystalline hydrogenated silicon (nc-Si:H) have attracted a lot of attention because of their potential applications in solar cells, thin film transistors, and [...]

Two series of polymers and copolymers containing oxadiazole units have been studied with respect to their photo-optical and electrochemical behavior. Fluorene units were introduced in the macromolecular chain together with oxadiazole rings in order to obtain a better balance between electrons and holes injection and transporting properties. Upon irradiation with UV light the polymers showed photoluminescence maxima in the blue spectral range. Cyclic voltammetry was performed in order to obtain information about the electrochemical stability and reversibility of the redox processes of these polyoxadiazoles. The highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels, and electrochemical and optical band gap values were calculated by using the results of cyclic voltammetry and UV/vis spectroscopy, respectively, showing very good electron injection and transport characteristics. POLYM. ENG. SCI., 54:1126-1133, 2014., INTRODUCTION Oxadiazole-containing polymers and organic small molecules are a topic of interest because of their unique properties arising from the presence of nitrogen-containing heterocyclic aromatic structure. Polymers containing 1,3,4-oxadiazole rings [...]

The article presents the efficient fabrication of the Poly[9,9-dioctylfluorenyl-2,7-diyl]-co-1,4-benzo-(2,1,3}-thiadiazole (F8BT) thin film using the electrostatic spray technique. Electrostatic atomization of the inhouse developed F8BT polymer ink was achieved at considerable low voltage. The structural and optical characterizations of the fabricated F8BT thin film were thoroughly investigated. Furthermore, the organic diode structure with electrostatic spray deposited F8BT thin film was fabricated and its performance was analyzed by performing current voltage measurement. The current-voltage characteristic curve of the organic diode showed nonlinear diode like behavior, thereby confirming the proper interference established between organic diode adjacent layers. The space charged limited current mechanism has been found to be dominant in the fabricated organic device with carrier mobility value Of 5.65 [e.sup.-4] [cm.sup.2][V.sup.-1][S.sup.-1]. POLYM. ENG. SCI., 54:675-681, 2014. © 2013 Society of Plastics Engineers, INTRODUCTION The development and commercialization of polymer semiconductors have made revolutionary progress because of the rapidly growing demand for printed electronic applications (1). Being low temperature and solution processable, polymer [...]

The photodetachment of [H.sup.-] ions in a nonuniform electric field has been investigated on the basis of closed orbit theory. Firstly, we give a clear physical description of the detached electron's movement in a nonuniform electric field. Then we put forward an analytical formula for calculating the photodetachment cross section of this system. Our study suggests besides the closed orbit previously reported for the photodetachment of [H.sup.-] in a uniform electric field, some additional closed orbits are produced owing to the effect of the nonuniform electric field. Compared with the photodetachment cross section of [H.sup.-] in a uniform electric field, the oscillation in the cross section of our system becomes much more complicated and the cross section exhibits a multiperiodic oscillatory structure. To show the relation between the oscillation in the photodetachment cross section and the detached electron's classical closed orbits clearly, we make a Fourier transformation for the scaled photodetachment cross section of this system. Each peak in the Fourier transformed cross section corresponds to the contribution of one closed orbit. This study provides a new understanding of the photodetachment of negative ions in the presence of a nonuniform electric field. PACS Nos.: 34.35.+a, 32.80.Gc, 32.80.Qk, 42.50.Hz. Nous etudions le photo-detachement de l'ion [H.sup.-] dans un champ electrique non uniforme, sur la base de la theorie de l'orbite fermee. Nous donnons d'abord une description detaillee du mouvement de l'electron detache dans un champ electrique non uniforme. Ensuite, nous proposons une formule analytique pour la section efficace de photo-detachement de ce systeme. En plus de l'orbite fermee prealablement rapportee pour le photo-detachement de [H.sup.-], notre etude suggere des orbites fermees additionnelles dues a la non uniformite du champ electrique. La comparaison avec la section efficace de photo-detachement de [H.sup.-] en champ electrique uniforme montre que l'oscillation de la section eficace de notre systeme devient beaucoup plus compliquee et cette section eficace presente une structure oscillante multiperiodique. Nous operons la transformation de Fourier de la section eficace de ce systeme ain de montrer clairement la relation entre l'oscillation de la section eficace de photo-detachement et les orbites classiques fermees de l'electron detache. Chaque pic de la transformation correspond a la contribution d'une orbite fermee. Ces resultats jettent une lumiere nouvelle sur le photo-detachement d'ions negatifs en presence d'un champ electrique non uniforme. [Traduit par la Redaction], 1. Introduction The photodetachment of [H.sup.-] in various external fields has been studied by many authors over the past 20 years. Pioneering measurements of the photodetachment cross section of [H.sup.-] [...]

The gamma irradiation technique has been used to alter the dielectric and electro-optical properties of a liquid crystal material. The present paper reports a comparative study of dielectric and electro-optical properties of unirradiated EBHA nematic liquid crystal (NLC) with gamma-irradiated EBHA NLC. The dielectric measurement has been performed with variation in voltage and temperature within the frequency range 100 Hz-10 MHz. Variations in response time for both gamma- irradiated and unirradiated samples have also been measured and are well explained in the present paper. PACS Nos.: 77.84.Nh, 78.20.Ci, 77.22.Gm, 76.80.+y, 78.20.Jq. Nous soumettons un cristal liquide a une irradiation gamma, afin de modifier ses proprietes dielectriques et electrooptiques. Nous comparons ici les proprietes dielectriques et electro-optiques d'un cristal liquide nematique (NLC) EBHA non irradie avec celles d'un NLC EBHA irradie. Les mesures dielectriques sont faites avec variation de voltage et de temperature dans le domaine de 100 Hz a 10 MHz. Nous mesurons et expliquons egalement les variations dans le temps de reponse pour les deux echantillons, irradie et non irradie. [Traduit par la Redaction], 1. Introduction The modification in dielectric and electro-optical properties of liquid crystal (LC) caused by ion beam radiation is a new field of research. Ionizing particles like electrons, photons, and [...]

The polyaniline (PANI) was synthesized using different dopant acids (iminodiacetic, methanesulfonic, phosphoric, and boron trifuoride) using oxidative polymerization method. These obtained new polymers were characterized by using spectrophotometric methods such as FTIR, UV-vis. The calculated value of the optical energy gap for the doped investigated polymer was reached to 3.70 eV for PANI-OH doped by boron trifuoride. The conductivity of the polymers was also investigated. The direct current (dc) conductivity as a function of temperature for the doped polymers has been studied. The results show increase in the conductivity with increase in temperature. Also, the value of dc conductivity at room temperature was found to be greater than that of the undoped PANI by nearly one to four orders of magnitude with respect to the used dopant acid. POLYM. ENG. SCI., 53:251-256, 2013. © 2012 Society of Plastics Engineers, INTRODUCTION With the discovery of intrinsically conducting polymers (ICPs) in 1960 (1), an attractive subject of research was initiated because of the interesting properties and its numerous application possibilities. ICPs [...]

The systematic trends of electronic structure and optical properties of Ru[O.sub.2] consisting of its four phases have been studied by using norm-conserving pseudopotential within the generalized gradient approximation for the exchange- correlation potential. The total density of states (DOS) and energy band structure investigations revealed that the fluorite phase possesses the broadest conduction bandwidth (0-30 eV) and the pyrite phase possesses the narrowest conduction bandwidth (0-5 eV). Study on partial DOS we found that O 2p electrons of the fluorite phase present a significant shift towards the Fermi level and Ru s and p electrons of the rutile phase contribute little to the orbital energy level formation. For the first time, we found that the norm-conserving pseudopotential failed to obtain the normal DOS and energy band distributions for a rutile Ru atom below about -10 eV, whereas such missing electronic distributions could be obtained successfully using an ultrasoft pseudo potential. Investigations on the optical properties further found that the rutile and Ca[Cl.sub.2]-type phases behave more similarly and the fluorite phase shows the most sensitive response in the whole radiation reaction region. The electron energy loss function revealed that the pyrite phase corresponds to the least relative intensity. PACS Nos: 63.20.dk, 71.20.-b, 78.20.Ci Nous utilisons un pseudo-potentiel a norme conservee dans l'approximation du gradient generalise pour obtenir le potentiel d'echange-correlation, afin d'etudier les tendances systematiques de la structure electronique et des proprietes optiques du Ru[O.sub.2], incluant ses quatre phases. La densite totale d'etats (DOS) et la structure de la bande d'energie revelent que la phase fluorite possede la plus grande largeur de bande de valence (0-30 eV) et que la phase pyrite possede la plus etroite (-20-0 eV). Etudiant les DOS partielles, nous trouvons que les electrons 2p de O dans la phase fluorite montrent un deplacement marque vers le niveau de Fermi, alors que les electrons s et p du Ru dans la phase rutile contribuent peu aux niveaux d'energie orbitaux. Pour la premiere fois, nous trouvons que le pseudo-potentiel a norme conservee echoue a obtenir la DOS normale et les distributions de bande d'energie pour le Ru rutile sous -10 eV, alors que de telles distributions sont obtenues avec succes a partir de pseudo-potentiels ultra mous. Etudiant les proprietes optiques, nous trouvons que les phases rutile et du type Ca[Cl.sub.2] sont plus proches et que la phase fluorite a la reponse la plus sensible sur toute la region de reaction radiative. La fonction de perte d' energie electronique revele que la phase pyrite a la plus faible intensite relative. [Traduit par la Redaction], 1. Introduction The low resistivity and reactivity of Ru[O.sub.2] has made it technologically important as a strip-line conductor in integrated circuits, as a diffusion barrier in contact metallizations, etc. [1, [...]

A sandwich immunoassay is a powerful tool for identifying a specific substance in a biological sample. However, its heterogeneous strategy always requires repetitive liquid handlings and long processing time. Here an optoelectrofluidic immunoassay platform for simple, fast, and automated detection of human tumor marker based on surface-enhanced Raman scattering (SERS) has been developed. By using a conventional optoelectrofluidic device and a liquid crystal display module, simple and quantitative detection of human tumor marker, alpha-fetoprotein, in a ~500 nL sample droplet has been automatically conducted with lower detection limit of about 0.1 ng/mL within 5 min. This study depicts the first practical application, for protein detection, of the optoelectrofluidic manipulation technology. This image-driven immunoassay platform opens a new way for simple, fast, automated, and highly sensitive detection of antigens. 10.1021/ac101325t

Optical addressing of semiconductor electrodes represents a powerful technology that enables the independent and parallel control of a very large number of electrical phenomena at the solid-electrolyte interface. To date, it has been used in a wide range of applications including electrophoretic manipulation, biomolecule sensing, and stimulating networks of neurons. Here, we have adapted this approach for the parallel addressing of redox reactions, and report the construction of a DNA microarray synthesis platform based on semiconductor photoelectrochemistry (PEC). An amorphous silicon photoconductor is activated by an optical projection system to create virtual electrodes capable of electrochemically generating protons; these PEC-generated protons then cleave the acid-labile dimethoxytrityl protecting groups of DNA phosphoramidite synthesis reagents with the requisite spatial selectivity to generate DNA microarrays. Furthermore, a thin-film porous glass dramatically increases the amount of DNA synthesized per chip by over an order of magnitude versus uncoated glass. This platform demonstrates that PEC can be used toward combinatorial bio-polymer and small molecule synthesis. combinatorial chemistry | genomics | opto-electronics | phosphoramidite | solid-phase synthesis

Increasing legislation has steadily been introduced throughout the world to restrict the use of heavy metals, particularly cadmium (Cd) and lead (Pb) in high temperature pigments, ceramics, and optoelectronic material applications. Removal of cadmium from thin-film optical and semiconductor device applications has been hampered by the absence of viable alternatives that exhibit similar properties with stability and durability. We describe a range of tin-based compounds that have been deposited and characterized in terms of their optical and mechanical properties and compare them with existing cadmium-based films that currently find widespread use in the optoelectronic and semiconductor industries. OCIS codes: 240.0310, 310.0310, 310.1860, 310.3840, 310.6188, 310.6860.

We describe the mathematical and conceptual foundations for a novel methodology for jointly optimizing the design and analysis of the optics, detector, and digital image processing for imaging systems. Our methodology is based on the end-to-end merit function of predicted average pixel sum-squared error to find the optical and image processing parameters that minimize this merit function. Our approach offers several advantages over the traditional principles of optical design, such as improved imaging performance, expanded operating capabilities, and improved as-built performance. OCIS codes: 110.0110, 100.6640.

We describe the concept of a vision system based on an optoelectronic hardware neural processor. The proposed system is composed of a pulse coupled neural network (PCNN) preprocessor stage that converts an input image into a temporal pulsed pattern. These pulses are inputs to the optical broadcast neural network (OBNN) processor, which classifies the input pattern between a set of reference patterns based on a pattern matching strategy. The PCNN is to provide immunity to the scale, rotation, and translation of objects in the image. The OBNN provides high parallelism and a high speed hardware neural processor. OCIS codes: 100.0100, 200.4700.

The article describes the design and performance of an InGaAsP-InP 1 x 2 reconfigurable waveguide digital optical switch (RW-DOS) actuated by carrier-induced refractive index modulation. The optimized InGaAsP-InP devices are found to have required less than 20-mA drive current and exhibited better than 25-dB switching contrast ratio.

A time-resolved microwave conductivity (TRMC) is used to study the photoinduced interfacial charge carrier generation, separation, trapping, and recombination in Ti[O.sub.2]/[In.sub.2][S.sub.3]/CuIn[S.sub.2] solar cells. The results provide insight into the role of the [In.sub.2][S.sub.3] buffer layer which leads to the formation of long-lived mobile charge carriers and the application of TRMC method to study optoelectronic processes at semiconductor interfaces.

Organic semiconductor materials for lasers are discussed followed by resonator design, fabrication, progress toward applications, and future challenges. Such organic semiconductors combines novel optoelectronic properties with simple fabrication and the scope for tuning the chemical structure to give desired features, making them attractive candidates as laser materials.

The studies related to ruthenium tris-bipyridine dyes containing oligophenyleneethynylene (OPE) rigid rod linker groups and the effect of the rigid rod on their optoelectronic properties is reported. The findings suggest that both the absorption spectra and the redox properties of the dyes with OPE rods are sensitive to the environment.

Camera motion estimation in image sequences generally focuses on the recovery of the frames when the camera is mounted on a moving platform. Global motion in video sequences is more complex and involves camera operation, camera motion, and other nontarget motions. Global motion compensation is usually handled by compensating the dominant motion using estimation and segmentation techniques. To enhance tracker performance and accuracy, frame recovery operation plays a crucial role by estimating undesired motion. In this paper, a normalized correlation-based regional template-matching (TM) algorithm has been developed to accurately recover frames before the application of the tracking algorithm. Then, a robust multiple-target-tracking system has been developed using a combination of fringe-adjusted joint transform correlator and TM techniques. Joint transform correlation detects a target optoelectronically, while TM technique is performed digitally. To increase the tracking system speed and decrease the effects of clutter, a subframe segmentation and local deviation-based image-preprocessing algorithm has been proposed. The improved performance of multiple-target-tracking system is tested using real-life forward-looking infrared (IR) imagery video sequences obtained from IR sensors mounted on an airborne platform. Index Terms--Fringe-adjusted filter (FAF), global motion compensation, joint transform correlation (JTC), optoelectronic target detection technique, target tracking.

The history of physics in Cuba is connected to Cuba's relationships with the Soviet Union, other socialist countries, Latin America and Europe and it also reflects the strength, character, and resilience of the Cuban people. The contribution of Cuban physicists in the areas of condensed matter and materials physics, solar energy, optoelectronics and medical physics are discussed.

Conventional inclination measurement systems such as precision vials and capacitance measuring systems can measure inclination in only one direction at a time. We present what is believed to be a new optoelectronic system that can measure inclination angles along two orthogonal directions simultaneously by using a simple pendulum, two mirrors, a 2D position-sensing detector (PSD), and a laser diode. The light ray from the laser is projected onto a mirror that is fixed to a pendulum whose relative angle modifies in response to inclination changes of the inclinometer's housing. The light ray reflected by the mirror is sensed by the PSD, after which the signal can be interpreted by a PSD signal processor, recorded, or output to a computer. This study uses skew-ray tracing methodology to obtain implicit nonlinear system equations to model the relations of the relative inclination angles of the various components, PSD position, and world frame. A first-order Taylor series expansion is used to obtain a linear form of the system equations. To validate the proposed methodology, an actual prototype system is built and experimental results show that the performance of this system is excellent. OCIS codes: 080.2730, 080.2740, 120.4570, 120.4640.

The high bandwidth available in optoelectronic interconnects is often suggested as making them suitable for use in high-performance computer systems. However, it will be shown that for problems where message sizes are small, the latency of an optoelectronic interprocessor interconnect will place a lower limit on the number of processors required to produce performance enhancement over a traditional electronic interconnect. OCIS codes: 200.2610, 200.4650.

An adaptive joint transform correlator for real-time pattern recognition is presented. A reference image for the correlator is generated with a new iterative algorithm. The training algorithm is based on synthetic discriminant functions. The obtained reference image contains the information needed to reliably discriminate a target against known false objects and a cluttered background. Calibration lookup tables of all optoelectronics elements used are included in the design of the adaptive joint transform correlator. Two methods for the implementation of the proposed joint transform correlator in an opto-digital setup are considered. Experimental results are provided and compared with those of computer simulations. OCIS codes: 070.4550, 070.5010.

A multitap negative and positive coefficient radio-frequency transversal filter is implemented by using a digital-micromirror-device spatial light modulator for weighting-factor control and a chirped fiber Bragg grating for time-delay control. The demonstrated architecture is reconfigurable, has high speed and low loss, and is robust through digital programmability for a wide variety of filtering algorithms. A design using an interleaver for differential detection realizes an ultrahigh bandwidth with a maximum processable frequency of 33.7 GHz. A multitap low-pass filter, a negative tap notch filter with 40 dB attenuation, and a multitap negative coefficient bandpass filter are experimentally demonstrated. The results are in agreement with theory.

A mean field Mori-Tanaka model is developed to calculate the effective magnetoelectrostatic moduli of matrix-based multiferroic composites, in terms of the shape aspect ratio, volume fraction and orientation distribution of second phase particles. It is observed that laminated composites are optimal for magnetoelectric coefficient a(sub 11) while fibrous composites are optimal for a(sub 33) and also these coupling coefficients are maximum when the second phase particles are aligned.

Some of the unique issues involved in testing transmitter and receiver circuits for optoelectronic-very-large-scale-integrated (OE-VLSI) applications are reviewed. In particular, the problem of testing OE-VLSI chips prior to optoelectronic device integration is outlined. Based on circuit-level approaches such as fault sensitization and novel system-level testing methodologies, the first OE-VLSI chip with testable transmitters, receivers and digital circuitry was designed in 0.35-[micro]m CMOS. The operation of the ASIC was verified experimentally and a fault-coverage greater than 80% is obtained, for a test time in the hundreds of microseconds range. Yield improvements ranging from 10% to 25% are predicted. Index Terms--Design for testability, fault diagnosis, optoelectronic devices, optoelectronic-very-large-scale integration (OE-VLSI), yield estimation.

In recent years, optical technology has been incorporated into mechatronic systems at an accelerated rate, and as a result, a great number of machines/systems with smart optical components have been introduced. This integrated technology is termed 'optomechatronics.' This paper introduces the fundamental concept, definition, and characteristics of the technology by analyzing the characteristics of a variety of practical optomechatronic systems. The introduction describes how optical and mechatronic components are physically coupled to each other to form optomechatronic integration. With this observation, we describe the nature and integration concept of the technology, from which we can derive the technology-driven fundamental functionalities in some detail. Based upon the knowledge on basic optomechatronic integration and functions, we analyze optomechatronic systems in general from the viewpoint of system configuration and design and, thus, the roles of optical technology in overall system performance being learned and the synergistic effects due to its fusion with mechatronics being understood. Index Terms--Functional modules, mechatronics, optoelectronics, optomechanics, optomechatronic integration, technology fusion.

Ultrabright light emitting diodes (LEDs) are a new light source for visual psychophysics and microscopy. The new LEDs are intended primarily for room and exterior illumination, and the manufacturers' specifications are adequate for that. However, we use them as light sources in situations where a more complete characterization may be useful. For one set of LEDs we have measured the radiometric intensity and its distribution in space and wavelength, and we have tested for interactions of these variables and their dependence on driver configuration. We describe techniques for making these measurements and give a link to a simple calculator for converting among radiometric and photometric measures, as well as an evaluation of the safety considerations these very bright sources demand. OCIS codes: 230.6080, 230.3670, 120.5630, 120.0120.

A physical modeling and a rigorous theoretical analysis consisting of the two-temperature model and the generalized transmission-line model is used to evaluate a photo-induced terahertz continuous-wave voltage from a dc current-biased high-temperature superconducting (HTS) transmission line by optical heterodyne photomixing. The electrical and optical frequency-response analyses show the amplitude of this voltage increases with increasing beat frequency and decreasing optical frequency of laser beams. Its maximum frequency is found to be limited by the gap frequency of the HTS material, which is consistent with the available experiments reported in the literature. The developed model along with our numerical simulation reveal the ways to produce a coherent traveling-wave and high-power terahertz signal with proper choice of an HTS material, bias condition, geometrical configuration, and parameters of the transmission line and characteristics of two laser beams. This FITS photomixer can play an important role in terahertz transceivers as broadly tunable local oscillators with low-noise/low-power consumption characteristics. Index Terms--Photomixers, superconducting devices, superconducting optoelectronics, terahertz devices, terahertz photonics.

Readily formed at nanoscale break junctions, arrays of individual spatially isolated, strongly electroluminescent [Ag.sub.2]-[Ag.sub.8] nanoclusters perform complex logic operations within individual two-terminal nanoscale optoelectronics devices. Simultaneous electrical excitation of discrete room-temperature nanocluster energy levels directly yields AND, OR, NOT, XOR, and even full addition logic operations with either individual nanoclusters or nanocluster pairs as the active medium between only two electrodes. Imaged in parallel, noncontact electroluminescent readout obviates the need for electrically isolating individual features. This gated, pulsed, two-terminal device operation will likely drive future nano and molecular electronics advances without complicated nanofabrication.

A wave demultiplexer with N channels in a two-dimensional photonic crystal is described and discussed.

We present a simple electronic circuit that produces negative delays. When a pulse is sent to the circuit as input, the output is a pulse with a similar wave form that is shifted forward in time. The advance time or negative delay can be increased to the order of seconds so that we can observe the advance with the naked eye by observing two light emitting diodes that are connected to the input and the output. The negative group delay in the electronic circuit shares the same mechanism with superluminal light propagation, where the group velocity exceeds the speed of light or even becomes negative.

A critical issue identified in both the technology roadmap from the Optoelectronics Industry Development Association and the roadmaps from the National Electronics Manufacturing Initiative, Inc. is the need for predictive […]

The effect of proton irradiation of InGaAs/GaAs quantum-well (QW) light-emitting diodes (LEDs) has been studied at energies ranging from 1 to 500 MeV in order to determine device damage mechanisms. The data are analyzed in terms of the theory of Rose and Barnes, and complete correlation of the data over the entire proton energy range was achieved. This degradation data, along with data from other GaAs-based optoelectronic devices, are discussed in terms of the nonionizing energy loss (NIEL). The energy dependences of the various damage coefficients for proton energies greater than about 10 MeV are bounded by the total NIEL and the elastic NIEL. Index Terms--Displacement damage, nonionizing energy loss, optoelectronic.

A steady-state photoresponse analysis of thin superconducting film is described, based on the Bardeen, Cooper and Schreiffer (BCS) theory. The analysis is helpful for designing superconducting optoelectronic devices based on photo-excited superconducting film, and for designing optically controlled superconducting microwave devices.

Research describing a theory of rational harmonic mode locking is presented. In particular time domain analysis of ring fibre lasers is investigated for pulse train propagation.

The behaviour of transverse and longitudinal optical photons in hexagonal AlxGa1-x N films is investigated.

A new study uses low-temperature photoluminescence measurements and x-ray diffraction to investigate relationship between quantum well number and strain relaxation in InGaN/GaN multiple quantum wells.

A new study examines the current spreading for unipolar semiconductor lasers, focusing on an AlInAs/GaInAs quantum cascade laser.