In this research, the authors give an analysis of surface structural morphology and optical waveguide properties of gadolinium oxide (Gd₂O₃) and gadolinium oxide europium doped (Gd₂O₃:Eu³⁺) films as prepared via the sol-gel and dip coating methods under atmospheric and clean room conditions. After describing sol-gel preparation routines, the authors further give observations of homogeneous surface morphological as characterized with scanning electron microscope (SEM) techniques. In addition, FTIR measurements of the Gd₂O₃ and Gd₂O₃:Eu³⁺ films and sol gels were made to monitor the decomposition and oxidation reactions that occur during processing. The samples' structural and resulting optical properties were studied and compared according to film thickness and surface morphological features.

We analyze laser-induced periodic structure developing in a semiconductor under the condition of both optical bistability existence and external electric field presence. Optical bistability occurs because of nonlinear dependence of semiconductor absorption coefficient on charged particles concentration. This dependence of the semiconductor absorption takes place due to the Burstein-Moss effect. The electron mobility, diffusion of electrons, and laser-induced electric field are taken into account for laser pulse propagation analyzing. We found out that an external electric field could induce helical auto-waves of high absorption domain in semiconductor if electron mobility influences on electron motion. The electron mobility causes electron motion from high absorption domain to domains with lower concentration of free charged particles. As a consequence, the laser energy absorption increases in these domains and new domains with high absorption appear. External electric field together with electric field of free electrons and ionized donors governs the electron motion. As a result, at certain conditions the additional positive inverse loop between electron motion and electric field caused by redistribution of free charged particles appears. Together with an explosive absorption existence, which arises from optical bistability, as a result of these two mechanisms presence the helical wave for free charged particles concentration of electron-hole plasma in semiconductor develops. Such type of wave may be seen also for a propagation of laser pulse with micro-, and nano-, and picoseconds duration because an optical bistability based on increasing absorption takes place for effecting of these pulses as well. For computer simulation of a problem under consideration a new finite-difference scheme is proposed. The main feature of proposed methods consists in constructed iterative process.

We report a unique technique to generate a liquid periodic structure whose unit volume is as low as a few hundred femto-liter. Liquids such as water, toluene and ethanol were filled in a hollow optical fiber (hole diameter of 8 and 13μm), which were locally heated by a traversing miniature electric furnace. The periods between droplets could be varied flexibly in the range from 14 to 100μm and the volume of individual droplet was in the range from 112 to 845 femto-liter. We also fabricated the periodic liquid droplets with quantum dots, whose fluorescence was successfully measured in each droplet. These periodic liquid droplets could serve as flexible liquid long period fiber grating for the hollow optical fiber, which can be further applied in various mechanical and bio-chemical sensors

For monitoring the optical properties of material under a dynamical processing, we design a compact in-situ ellipsometry by using a liquid crystal (LC) phase retarder. Since the key issue of an accurate ellipsometer is the alignment of each optical component in the system, hence we not only proposed the alignment procedure, we also calibrated the phase retardation of LC retarder for this in-situ ellipsometry. The azimuths of polarizers and phase retarders can be aligned by the analytical solutions of the azimuthal deviations. The phase retardation can be directly determined by the intensity ratio technique.

Ferroelectric thin films are used as high dielectric constant capacitors, infrared detectors, piezoelectric transducers, optical modulators, optical waveguides, and nonvolatile memory chips for dynamic random access memory (DRAM) etc. While ferroelectric and dielectric properties of these films have been extensively investigated, their optical properties have been comparatively less studied and of limited use in quantitative evaluation of multilayer thin films. In this work we explored the variable angle spectroscopic ellipsometry (VASE) technique for its effectiveness in physical property characterization. The VASE combined with its computer modeling tool enables nondestructive, nonintrusive, and contactless optical means for optical characterization. Crystalline Lead Zirconium Titanate PbZr_0.52Ti_0.48O₃ (PZT) thin films, fabricated on SrTiO₃ layer atop of Si substrates, were characterized using VASE (J.A. Woollam; Lincoln, NE, USA) by determining the ellipsometric parameters Ψ and Δ as a function of wavelengths (200-1000 nm) and incident angles (65°, 70°,75°) at room temperature. A physical representation of the multilayer system was constructed by a six layer model (analysis software WVASE32, J.A. Woollam) through a step-by-step method. Other physical properties characterized by several well-known techniques on structure, morphology and topographical features correspond well with the models developed using VASE alone. The technique and the methodology developed have shown promises in identifying the respective thickness and optical properties of multilayer thin film system, with limited input of processing or composition information.

We report on fabrication and investigation of optical and morphological properties of highly efficient (a quantum yield of 1%) upconversion polymer-inorganic nanocomposite thin film emitters prepared by the new technique of double beam matrix assisted pulsed laser evaporation (DB-MAPLE). Polymer poly(methyl methacrylate) (PMMA) host was evaporated on a silicon substrate using a 1064-nm pulsed laser beam using a target made of frozen (to the temperature of liquid nitrogen) solution of PMMA in chlorobenzene. Concurrently, the second 532-nm pulsed beam from the same laser was used to impregnate the polymer host with the inorganic nanoparticulate made of the rare earth upconversion compounds NaYF_4: Yb^3+, Er^3+, NaYF4: Yb_3+, Ho^3+, and NaYF₄: Yb^3+, Tm^3+. The compounds were initially synthesized using the wet process, baked, and compressed in solid pellet targets. The proposed DB-MAPLE method has the advantage of making highly homogeneous nanocomposite films with precise control of the doping rate due to the optimized overlapping of the plumes produced by the ablation of the organic and inorganic target with the infrared and visible laser beams respectively. X-ray diffraction, electron and atomic force microscopy, and optical fluorescence spectroscopy indicated that the inorganic nanoparticulate preserved its crystalline structure and upconversion properties (strong emission in green, red, and blue bands upon illumination with 980-nm laser diode) after being transferred from the target in the polymer nanocomposite film. The produced films can be used in applications varying from the efficiency enhancement of the photovoltaic cells, optical sensors and biomarkers to anti-counterfeit labels.

The characteristics of self-pulsing in a large mode area, end-pumped, double-clad Yb-doped fiber laser are presented. The laser operates in a self-pulsing regime either by using one or two perpendicularly cleaved ends as the feedback mirrors while it transforms in a broadband amplified spontaneous emission source when both ends are angle cleaved. In the pulsed regime, up to 2 microseconds FWHM pulse widths and repetition rates of the order of hundreds of kHz are generated.

Uniform intensity of laser radiation is very important in holographic and interferometry technologies, therefore transformation of typical Gaussian distribution of a TEM00 laser to flat-top (top hat) is an actual technical task, it is solved by applying beam shaping optics. Holography and interferometry have specific requirements to a uniform laser beam, most important of them are flatness of phase front and extended depth of field. There are different refractive and diffractive beam shaping approaches used in laser industrial and scientific applications, but only few of them are capable to fulfil the optimum conditions for beam quality demanding holography and interferometry. We suggest applying refractive field mapping beam shapers piShaper, which operational principle presumes almost lossless transformation of Gaussian to flat-top beam with flatness of output wavefront, conserving of beam consistency, providing collimated low divergent output beam, high transmittance, extended depth of field, negligible wave aberration, and achromatic design provides capability to work with several lasers with different wavelengths simultaneously. This approach is used in SLM-based technologies of Computer Generated Holography, Dot-Matrix mastering of security holograms, holographic data storage, holographic projection, lithography, interferometric recording of Volume Bragg Gratings. High optical quality of resulting flat-top beam allows applying additional optical components to vary beam size and shape, thus adapting an optical system to requirements of a particular application. This paper will describe design basics of refractive beam shapers and optical layouts of their applying in holographic systems. Examples of real implementations and experimental results will be presented as well.

A single mode microstructured polymer optical fiber has been designed and analysed based on finite element method (FEM). The design parameters of proposed microstructured polymer optical fiber structure have been optimized to obtain single mode operation along with mode area of 895 μm². The differential loss between fundamental and higher order modes of structure have been obtained very large (~10³) with negligible loss of fundamental mode. The proposed structure is effectively single mode at 632.8 nm wavelength after the short distance 1.65 m with very low loss of guiding mode. The proposed structure is applicable for high power delivery devices.

Multimode Interference devices are analyzed semi-analytically using matrix approach. The propagation constant and mode profile of different modes of a multimode waveguide are determined. The field intensity for the combination of all the modes at different propagation distance is also obtained. The results are in accordance to the theory. The method can be extended to a singlemode-multimode-singlemode device where the concept of overlap integral is introduced at their interface. As this method consists of multiplication of 2X2 matrices, it is simple and computationally fast

In this study, binary CdSe and ternary Zn_0.5Cd_0.5Se quantum dots (QDs) with monochromatic light are blended with conventional phosphors and those monochromatic lights of Zn_0.5Cd_0.5Se QDs are also mixed together and then packaged as remote type. Besides, white light CdSe QD are used alone to fabricate white light-emitting diode (LED). We have demonstrated that the color rendering index (CRI) and luminous efficacy can be improved by blending conventional phosphors with QDs. The Zn_0.5Cd_0.5Se QDs incorporated with yellow phosphors have better device performance and optical properties. Zn_0.5Cd_0.5Se QDs with different emission wavelength are blended with each other. The result reveals that mixing ratios and photoluminescence efficiency (PLE) between different colors of QDs are important factors. When white CdSe QD is excited by ultraviolet LED (UV-LED) without mixing multi-colors of phosphor, high CRI can be obtained for CdSe-based white LED.

Here we propose a simple design for a solid-core photonic crystal fiber made of silica by keeping the golden ratio (1.618) between pitch and air hole diameter Λ /d in a subset of six rings of air-holes with hexagonal arrangement. In the case when we have a pitch equal to one micron (Λ =1 μm), we need air-holes diameters d=0.618 μm in order to obtain the golden ratio parameter (Λ/d=1.618), and achieve two zero dispersion wavelength (ZDW) points at 725 nm and 1055 nm; this gives us the possibility to use this fiber in supercontinuum generation using a laser emission close to that points. We analyzed a series of fibers using this relation and show the possibilities of tunable ZDW in a wide range of wavelengths from 725 nm to 2000 nm with low losses and small effective area. In agreement with the ZDW point needed, the geometry of the structure can be modified to the point of having only three rings of air holes that surround the solid core with low losses and good confinement mode. The design proposed here is analyzed using the finite element method (FEM) with perfectly matched layers (PML), including the material dispersion directly into the model applying the Sellmeier’s equation.

Holographic three-dimensional (3D) display is a promising technique since it can present a 3D scene with all characteristics of real-world objects. Volume holography provides big data capacity for high resolution 3D display. It has the advantages of good wavelength and angular multiplexing properties over planar holography because of the Bragg condition. 3D display can be realized by recording holographic kinoforms into a volume holographic polymer. The purephase wavefront of a 3D object is generated and uploaded by a phase-only spatial light modulator. The phase-modulated data page is recorded in the volume holographic photopolymer. The 3D object can be reconstructed at a designed distance behind the volume holographic polymer by illuminating with the reference beam. Volume holographic kinoform can realize high-resolution 3D display without any lens or glasses by improving the space-bandwidth product of the display system.

In this paper, tunable spectrum LED based on nanostructured substrate is presented. In particular, the relationship between the temperature distribution and the nanostructured substrate is quantitatively simulated. The simulation results suggest that there can be a noticeable change in the temperature profile due to the existence of micro/nanostructured substrate. Such a change in the temperature distribution can result in a change of indium composition of InGaN/GaN LED, which in turn tune the output spectrum of LED.

Photonic crystal based nano -displacement sensor for horizontal as well as vertical displacement has been proposed. The design is highly sensitive in the displacement region 40nm–120nm with sensitivity 0.00461nm^-1 for horizontal displacement of the moving PhC waveguide. For vertical displacement of the moving PhC waveguide the design is highly sensitive in the region 150nm-200nm with sensitivity 0.00684nm^-1 for zero horizontal displacement, 130nm- 200nm with sensitivity 0.00523 nm^-1for 10nm horizontal displacement, 130nm-200nm with sensitivity 0.00418 nm^-1 for 20nm horizontal displacement, 130nm-200nm with sensitivity 0.00461 nm^-1for 30nm horizontal displacement,100nm-130nm with sensitivity 0.00466 nm-1for 40nm horizontal displacement. It has been concluded that the proposed design behaves as a Nano-displacement sensor for horizontal displacement of the moving PhC waveguide up to the region of displacement of magnitude of 400nm and for vertical displacement of the moving PhC waveguide up to the region of displacement of magnitude of 300nm.The proposed design can behave as a nano-Displacement sensor for both horizontal as well as vertical displacement.

A new design of the As2Se3 microfiber has been presented. With the optimized geometric parameters: pitch Λ= 0.8 μm and five different air filling ratios varying from 0.4 to 0.95, the structure exhibits an all normal dispersion with a flat top equal to -2.3 [ps/(nm.km)], a confinement loss less than 10^-2 dB/km, and a large nonlinear coefficient equal to 7250 (w. km)^-1. Using the generalized nonlinear Schrödinger equation, we generate a very broadband supercontinuum (SC) in the mid-infrared region. By pumping the fiber at λp=5.24 μm with a femtosecond laser having 50 fs as a width with a relatively low energy of E=80 pJ, we generate a large spectrum extending from 2 μm to 10 μm in only 2 mm fiber length. The generated SC demonstrates perfect coherence property over the entire bandwidth. SC generation extended into the mid-infrared (IR) spectral region have potential usefulness in a variety of applications requiring a broad mid-IR spectrum such as fiber sensing, IR spectroscopy, fiber laser, optical tomography coherence.

In this paper, a review on mid-IR supercontinuum generation (SCG) and its applications is presented. First, the physical mechanism of the supercontinuum generation in IR crystal fiber is introduced. Second, the recent progress on IR single crystal fiber, in particular ultrathin core double cladding IR single crystal fiber is described. Third, the transmission characteristics of mid-IR crystal fiber is illustrated. Fourth, the mid-IR supercontinuum generation in IR single crystal fiber is presented. Finally, the application of IR supercontinuum for smart target recognition is illustrated

Photorefractive (PR) hybrid liquid crystal (LC) cells have combined the space-charge field generated in either a polymer (using e.g. PVK;C₆₀) with the large birefringence from a LC layer to generate PR grating for beam coupling applications. The efficiency of PR beam coupling in hybrid devices is dependent on the amplitude of the space-charge field, as well as the ability of the LC molecules to align with the corresponding field. In this paper the time dynamics of the formation of the PR gratings are measured in LC hybrid systems and are used to explain the large variation of gain coefficients found in the literature.

In this paper the dependence of the coherence time of a femtosecond spectral supercontinuum from different initial pulse parameters - wavelength, peak intensity and duration is studied. The obtained dependences and ratio of the coherence time of the pulse to the duration of the pulse at the output are analyzed. It is shown that in the case of femtosecond spectral supercontinuum generation in fused silica in the areas of normal, anomalous and zero group velocity dispersion, with an increase of the central wavelength of the femtosecond laser pulse at the input, the coherence time of the radiation with ultra-wide spectrum is significantly decrease. However, in the region of zero group velocity dispersion of fused silica there is a "leap" of the coherence time. For example, for the initial pulse duration of 40 fs at 800 nm, the coherence time is 22 fs. With the increase of wavelength, the coherence time reduces to 4 fs at a wavelength of 1180 nm. In the area of zero group velocity dispersion, the coherence time increases dramatically to 20 fs, after which it decreases, reaching a minimum of 4 fs at a wavelength of 1560 nm.

In this paper, a new type of waveguide switch-field induced dynamic optical waveguide switch is presented. The switching mechanism is based on electric-field induced dynamic waveguiding effect in nanodisordered potassium tantalate niobate (KTN) crystals. By applying an electric field at different locations, different waveguide paths are created, which result in different output locations. The major advantages of this unique optical switch are broad bandwidth, covering the entire 1300 nm – 1600 nm fiber optic communication window, and ultrafast switching speed (on the order of nanosecond), which can be very useful for next generation optical networks such as the one used in data center networks.

Holographic interferometry is an effective and rich method for measuring very small (order of a wavelength) deformations of an object and is widely used for non-destructive testing. In this work, the use of photorefractive materials for implementing real time phase shifting holographic interferometry is examined in detail. Bragg and non-Bragg orders generated during two- and multi-beam coupling in a photorefractive material can be used to retrieve the deformation of the object, or the phase information of the object. In previous work, it has been shown that object deformation can be determined from monitoring Bragg and non-Bragg orders. Preliminary experiments for determining the depth profile of an object have been reported, along with approximate analytic solutions for the Bragg and non-Bragg orders for the case of interacting plane waves. In this work, the exact solutions of Bragg and non-Bragg orders are found from numerically solving the interaction equations in a photorefractive material. It is shown that if the grating written in the material using two waves is read out by a reference and the object, the resulting Bragg and non-Bragg orders contain the information of the object phase, and is dependent on material parameters and the writing and reading beam intensities. Similarities and differences between this dynamic holographic technique and the traditional phase shifting digital holography are extensively discussed.

Basic challenges for mid-infrared (MIR) Si photonics are developing of appropriate sources and detectors, detection sensitivity, size minimization and downscaling to a single-platform, spectral tunability. We address such challenges via proper design, modeling and material choice for a series of photonic structures. Our research is done in three steps: modeling, fabrication, characterization. The modeling starts with ellipsometry investigation of Si, Si₃N₄ and SiOx, to estimate the materials’ complex dielectric function ε =ε _r + i ×ε _i in MIR. The technique showed Si and SiN optical transparency in the range λ=4.5-6.5 μm, and negligible absorption for SiOx, which makes it appropriate for MIR photonics (Figure 1). Figure 2 demonstrates the device concept: MIR source emits electromagnetic field, which is coupled to/from a Siwaveguide (WG) via grating couplers. The WG performs as interaction medium between the propagating field and fluid atop the WG. It results in field attenuation, measured at the output, due to partial absorption by the fluid. To achieve efficient device performance, size, spectral tuning and evaluation of the attenuation, the structures were investigated by means of 3D photonic simulations. The structures were fabricated via the 200-mm-wafer-CMOS technology in Infineon involving deep-UV lithography and Bosch etching. PhC structures were fabricated as holes in a Si-slab with SiOx-filling to avoid residuals from the fluid into the holes, which modifies the photonic band gap and device sensitivity. Figure 3 shows SEM images of the structures. Our paper discusses the design, material characterization, single-platform integration of the source, WG and detector and first experiments with recently fabricated prototypes.

This paper aims to inform those interested in the scientific work of a large group of scientists: workers of the Department of Electronics and Optical communications of St. Petersburg State University of Aerospace Instrumentation in collaboration with workers of the Department of Quantum Electronics of St. Petersburg State Technical University in the area of researches and development of acousto-optic tunable filters (AOTF). Paper discusses the important features of the AOTF structure and their parameters that affect its work, such as: spectral range of optical radiation, spectral resolution, active aperture of the optical radiation, optical transmission of the working spectral range, optical radiation polarization (linear, circular or arbitrary) , diffraction efficiency, contrast, distortion of the optical radiation’s front, frequency range of elastic waves, switching time, maximum electric control power, impedance. Also the AOTF using is considered: AOTF’s implications for control of laser radiation, AOTF’s application to determine the counterfeit money. The last part of the report focuses on materials that act as antireflection thin films. Spectral characteristics of "clean" and enlightened substrates of ZnSe and Ge are shown. As seen from the examples in the report, antireflection thin films increase transmittance of optical elements.

An equiangular spiral (ES) photonic crystal fiber (PCF) design in tellurite glass has been presented. The structure parameters have been tailored for zero dispersion wavelength (ZDW) at λZDW=1570 nm. The fiber structure has high nonlinearity (γ = 2000 w^-1 Km^-1) at 1550 nm wavelength with very low and flat dispersion -0.152 [ps/(nm×km)]. We have generated supercontinuum using only 2 mm length of tellurite ES PCF with low input pulse energy of 200 pJ by pumping at 1550 nm. The proposed fiber may be a suitable candidate for nonlinear applications.

The idea of acousto-optic self-tuning deflector, which automatically returns the position of the acoustic line, corresponding to the mode of Bragg diffraction feedback implementation is proposed. Features of sodium bismuthate’s double molybdate grown by new technology – low gradient Czochralski process are illustrated.

Although, several reviews have appeared on various physical properties and applications of chalcogenide glasses, there is no thorough study of local atomic structure and its modification for eutectic Ge-Sb-Te alloys doped with Bi. Ge₂Sb₂Te₅ pure and Bi-doped films were deposited by ion-plasma sputtering method of synthesized GTS material on Si (100) and glass substrates coated with a conductive Al layer which was used as a bottom electrode. Current–voltage characteristics of different points of the same samples have been measured. Random distribution of inclusions within the sample made it possible to investigate the dependence of switching and memory effects on the phase composition at a constant value of other parameters. Measurements in the current controlled mode clearly showed that the memory state formation voltage does not depend on current in a wide range. Results indicate that the development of imaging technologies phase memory cells need to pay special attention to the conditions of Ge-Sb-Te film preparation. To increase the number of cycles “write – erase” should be additional prolonged annealing of the synthesized films.

Design studies method of star sensor thermal stability with liquid cooling using modern CAD has been described. Optimal operation of two circuits for liquid cooling structure of star sensor has been chosen using a mathematical model for calculating the convective heat transfer coefficient. Study defined the angular displacement of the star sensor with liquid cooling (~ 0.3 arc seconds), which is acceptable for star sensors with 1 arc seconds accuracy. At this level of scientific investigation the developed 3D model of the star sensor assembly comprising a thermally stabilizing ground test equipment allows to determine the angular error due to the temperature loads and optimal parameters liquid of cooling system (for example, the flow rate of fluid , geometrical parameters of cooling circuits , etc.). In the future, this model should be improved, which will consider the impact of other factors (e.g. gravity, vibration, etc.) on the performance of the star sensor.

We propose a new step imaging method based on astigmatism Fourier transform for synthetic-aperture ladar imaging processor, which is mainly used in optical imaging processing system of synthetic-aperture imaging ladar. The time-domain data is translated into spatial coordinate expression suitable for space optical conversion. The Fourier transform is realized by astigmatism principle. It can simultaneously achieve radar goals focusing both on distance and azimuth. Processor scale is effectively reduced. The process of target echo confocal imaging data is simplified. The requirements of ladar imaging processing system are reduced. It has a great advantage in the synthetic-aperture imaging ladar target echo confocal imaging data processing.

We present an analysis of the guided modes of a one-dimensional photonic bandgap waveguide which consists of a low refractive index guiding layer sandwiched between two Bragg mirrors. The layers in the mirrors are aperiodically arranged according to the Kolakoski K(1; 2) substitutional rules and their parameters are chosen in such a way that the omnidirectional reflection is achieved. Using the transfer matrix formalism, both the bandgap conditions and dispersion characteristics of the guided modes of such OmniGuide structure are studied.

The absorption characteristic and nonvolatile holographic storage are investigated for the first time in Ce and Ru codoped LiNbO₃ crystals in this paper. The absorption spectra examination shows that there is a good optical transmission in the blue and violet wavelength range in the as-grown and oxidized samples. An absorption peak around 530nm induced by Ru can be found. A photochromic effect is observed through UV illumination experiment. Nonvolatile holographic recording is performed with different sensitizing and recording wavelength strategies. The results show that the highest recording sensitivity (0.050cm/J) and dynamic range (2.7 cm^-1) can be obtained with 514nm recording and 405nm sensitizing.

The fully conjugated poly[2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopenta [2,1-b;3,4-b′] dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)] (PCPDTBT) was a low energy gap (Eg) organic polymer material with polydispersity index (PDI) 1.3. It’s the highest occupied molecular orbital (HOMO) 5.2 eV, the lowest unoccupied molecular orbital (LUMO) 3.75 eV and Eg 1.45 eV. As compared with poly-(3-hexylthiophene) (P3HT), the lower Eg made the more absorption in the near-infrared (NIR) area. Its maximum absorption peak (λ_max) was near 800 nm. The optimal conversion efficiency (η_p) of single-layered PCPDTBT:PC61BM organic photovoltaic (OPV) device reached 2.44% when the weight ratio of PCPDTBT:PC61BM was 1:2.5. In this study, we changed weight ratio, layer thickness, and solvent to enhance the optoelectronic properties of OPV devices. Variations the layer thickness were processed and investigated leading to an optimum η_p of 2.62 % for a single layer OPV cell with layer thickness of 150nm. The PCPDTBT molecule packed more order when the solvent evaporated to go slow. However, it did not increase the crystal level of PCPDTBT molecule for enhanced η_p.

This study primarily employed poly-(3-hexylthiophene) (P3HT): [6,6]-phenyl C₆₁-butyric acid methyl ester (PC₆₁BM) solvent to produce single-layer organic photovoltaic (OPV) cell of single-layer bulk heterojunction (BHJ). The OPV cell structure is ITO/PEDOT:PSS/P3HT:PC₆₁BM/LiF/Al. In the process, we examined the optoelectronic properties of producing P3HT:PC₆₁BM single-layer OPV cells in various thicknesses of active layer, temperatures, and times of thermal pre- and post-annealing. The results showed that the maximum conversion efficiency (ηp) of single-layer OPV cells increased in crystal level of P3HT molecule from low temperature to high temperature process and effective contact area between active layer and metal cathode of device. Thus the ηp value of cells can reach 4.58% after pre- and post-annealing.

Thermal dissipation had an important influence in the quantum effect of light emitting diodes (LED) because it enables transfer the heat from electric device away from the heat to the aluminum plate that can be used for heat removal. In the industrial processing, the quality of the thermal dissipation decides by the gumming technique between the PCB and aluminum plate. In this study, we fabricated a ceramic thin film of diamond like carbon (DLC) by vacuum sputtering, soldered the substrate of LED light to enhance the heat transfer. The dielectric coatings were characterized by several subsequent analyses, especially the measurement of real temperature. The X-Ray diffraction (XRD) diagram analysis reveals those ceramic phases were successfully grown on the individual substrate. The results show DLC thin film coating fabricated by vacuum sputtering has lower sheet resistivity, higher hardness, critical load, and thermal conduction, 3.5 Wm^-1 K^-1 to the purpose. The real temperature showed DLC thin film couldn’t transfer heat enough and limited work temperature of LED successfully as compared to aluminum nitride.

In this work the analytical model of the scattering response of a highly Yb^3+/Er^3+-codoped phosphate glass microring resonator array is developed. The microscopic statistical formalism is used to simulate its performance as a wavelengthselective amplifier. The performance of the integrated add-drop filter was investigated based on the signal transfer functions for Through and Drop ports, correlated the with gain coefficient and its dependence on pump power, signal power and Yb^3+/Er^3+- dopants concentration. In consequence, microring arrays with gain operating in the near infrared spectral range and, in particular, in the 1.5-mm wavelength band (emission band of Er-doped fiber amplifiers and lasers, already used in several bio/chemical sensing tasks) are highly attractive.

We show the sensing of load by means mechanically induced long-period fiber grating (MLPFG) made by applying pressure by means a screw to a pair of grooved plates over single-mode fiber. We used a torquemeter in order to obtain precision in the adjustment screw and thus establish an equilibrium pressure applied to a specific region of the optical fiber to form the long-period grating mechanically induced fiber. The increase the torque to screw, the resonance wavelength of MLPFG increases its depth over 16 dB. We use a detector to observe the changes amplitude according to the fiber pressure.

We present the results from the fabrication and characterization of mechanically induced long period fiber gratings in polarization maintaining photonic crystal fiber (PM-PCF). A supercontinuum source in the range of 600nm - 1700nm is used. This source is generated using a micro-chip laser at 1064nm and a single mode fiber. A long-period grating is induced over 40mm long unjacketed PCF using a V-grooved aluminum plate. External pressure is gradually applied with a metal screw and a torque meter and a loss dip with resonance wavelength is observed. Low insertion losses are depicted from (1-3) dBm with a bandwidth of about 30nm and a loss dip around 15dBm. Sensitivity for this preliminary work is found at 27 dB/Lb. Several applications are potentially possible with the optimization of the transmission spectrum controlled by applied pressure.

We studied experimentally the granular structures prepared on the base of ZnO thin films. The influence of acceptor or donor complex, caused by oxygen vacancy and interstitial zinc atom, and impurities (Li or Ga) on the crystallite structure conductivity has been investigated. The effect of granule size and crystallite structure on conductivity and photoconductivity was studied. The new method for determination of electric current dependence on spatial coordinates in thin conducting film was developed, which allowed to diagnose a one-dimensional conductivity in ZnO:Ga films. The experimental results are interpreted on the basis of the scaling hypothesis and the percolation theory.

An approach using lithography techniques to fabricate a binary-encoded fringe pattern for projected fringe profilometry is described. The sinusoidal fringes are spatially encoded with a stream of binary stripes. Phase unwrapping is then performed based on the transmittance of the binary stripes. The period of the binary stripes can be enlarged by increasing the length of the encoded stream. Its tolerance of phase unwrapping is therefore increased. Advantages of the fringe pattern for phase unwrapping include (1) reliable performance for colorful objects, (2) unwrapped errors only confined in a local area, and (3) low computation cost..

A scanning approach using fringe projection techniques to perform the 3D profile measurement for a non-diffusive object is proposed. It employs a hologram as the fringe projection device. Even though the inspected object is nondiffusive, the proposed method can retrieve the 3D shape precisely. Surfaces with depth discontinuities can be retrieved very well.

An approach using the fringe projection technique to perform the 3D profile measurement for a plano-convex lens is proposed. A fringe pattern is illuminated onto the lens object, and a CCD camera is employed to record the transmitted fringes on the screen. Fringes on the obtained image are deformed both by the refractive index and the topography of the object, and are analyzable to retrieve the 3D shape.

In this paper, a scanning approach using fringe projection techniques to perform the 3D shape measurement for a complicated object is proposed. A fringe pattern is projected onto the inspected object. A CCD camera observes the projected fringes. The point of view of the CCD camera is the same as the projected fringes. Thus, shadowing caused by tilted fringe projection can be eliminated. The depth-of-field of the camera lens is short enough that only fringes within the focused area can be clearly observed. By moving the inspected object around the focused area along the depth direction, a set of images, which addresses the contour of the object with its corresponding depth, is obtained. Assembling the image contours with their corresponding depths, the 3D shape of the object is retrieved. Even though the depth discontinuity on the inspected surface is pretty high, the proposed method can retrieve the 3D shape precisely.

The electrooptic response of crystals becomes attenuated in the megahertz or higher frequencies where it is of the most use for communication systems. This research explores new possibilities of improved electrooptic interaction at high frequencies, discovered as a result of coupled electrooptic effects near selected piezoelectric resonances. Results suggest that for electrooptics the key to a large interaction at high frequencies is the gradient of the strain in a modulated crystal and the acceleration of the accompanying lattice waves. While strains tend to be damped, acceleration of the lattice wave retains its amplitude at high frequencies. This interaction is studied by a high frequency Laser Doppler Vibrometer and by numerical finite element analysis modeling using COMSOL. PMN-PT crystal was the primary material studied due to its large piezoelectric coupling and electrooptic coefficients. The dynamic displacement of the samples was measured over a broad range of frequencies, including the fundamental resonant modes and higher order harmonics where the mode structure becomes complex and not well described by existing analytical models.

The electromechanical coupling in piezoelectric materials has been widely studied however a unified view of this interaction as function of frequencies using different measurement techniques has not previously been available. This study examines and compares multiple optical based homodyne and heterodyne interferometry techniques for displacement measurement over a wide range of frequencies and including a comparison made by using a commercial Laser Doppler Vibrometer. Ferroelectric lead titanate PbTiO₃ with high ferroelectric strain is studied in this work. Frequency dependence of the electromechanical displacement is obtained using multiple techniques and the emphasis is given to near resonant frequency interrogations.

In this paper, ponderomotive force induced nonlinear interaction between terahertz wave and air plasmas is presented. It is found out that the dimension of THz wave can be altered by the ponderomotive force induced nonlinear interaction between terahertz wave and air plasmas. The amount of change also depends on the plasma frequency. The higher the frequency, the bigger the amount of change will be. This unique nonlinear interaction can be very useful for controlling, adjusting, and modulating Terahertz wave.