Composite Cr⁴⁺:YAG--Nd³⁺:YAG crystal fiber was grown by means of LHPG method. By using a high quality Nd³⁺:YAG as the seed and a sintered powder rod as the source rod, Cd⁴⁺:YAG can be readily grown on a Nd³⁺:YAG end surface. The grown crystal fiber was processed and laser action was demonstrated. Preliminary results showed that the crystal fiber is well suited to a compact passively Q-switched laser operation. A Q-switched laser output showing a 9 ns pulse duration, a 19 mW average output and a 10 kHz repetition rate was demonstrated.

The optical limiting characteristics of the methyl-red dye doped nematic liquid crystal (NLC) films have been tested, and an interesting dark spot phenomenon and a dynamic self-action diffraction ring pattern in the far field behind the sample cell have been observed. The time sequence of the dark spot formation and the dynamic self-action diffractino ring apperaance has also been investigated. We found that, with increasing the energy impinging on the sample cell, the dark spot accompanied by a single outer bright ring always appears and lasts until the multiple diffraction rings form. We also found that the dark spot with a single outer bright ring in the far field corresponds to the nonlinear section of the optical limiting characteristic curves of the doped NLC fimls, while the onset of the multiple diffraction rings corresponds to the input damage threshold of the doped NLC film limiters. Our experimental results show that the optical limiter based on the methyl-red dye doped NLC films has a quite low optical limiting threshold and an unusually low clamped output to eye safety. In this paper, we will present how we tested the optical limiting characteristics of the methyl-red dye doped NLC films and what kind of the typical test results we obtained in the experiments. We will theoretically analyze the optical limiting mechanisms of the methyl-red dye doped NLC films. We will also discuss the advantages and some limitations of the methyl-red dye doped NLC films. We will also discuss the advantages and some limitations of the methyl-red dye liquid crystal limiters, and propose several possible solutions to these limitations.

The pattern formation of hexagonal and square structure is obtained in dielectric barrier discharge in argon at atmospheric pressure. The temporal behavior of total light emission of square pattern is measured with optical method. The experimental results show that there are two current spikes in each half cycle of applied voltage in waveform of total light emission. The possible structure of the pattern is proposed, which has been proved partly by late experiment.

Antimony doped tin oxide films have been deposited on flexible substrates such as polyimide and polypropylene adipate. And the structural properties of the films have been investigated. The XRD measurements reveal that all of the obtained films were polycrystalline with the rutile structure. With increasing the substrate temperature and film thickness, the crystallinity of the resulting films is improved and the crystalline size becomes larger. The substrate temperature and film thickness dependence of crystallinity for the SnO₂:Sb films were further revealed by their atomic force micrographs, which is consistent with the XRD observations. The XPS details of the SnO₂:Sb films are also given. The tin core levels Sn 3d_5/2 are observed at 486.5 and 494.9 eV, respectively, while the O 1s peak is obtained at 530.6 eV. It can be seen that the oxygen peak in the spectra is asymmetric, which is due to the concealed Sb 3d peak. The gap between the Sn 3d_5/2 and Sn 3d_3/2 levels is approximately the same as in the standard spectrum of Sn.

A new light source was researched and designed for cultural relic illumination. It is composed of high bright red, green, yellow, bule and white LED. A cone axes ellipse reflector is used in order to utilize light energy of LED as early possible. The light transmits in optical fiber bundle and lights the cultural relic in different angles and directions. The spectrum of the whole light source system is from 410nm to 700nm. There are not IR and UV. The light illuminance is 301x. Lighting of LEDs is controlled by rectangle waveform constant current source to make temperature lower and efficiency of light higher. Noise is avoided because a wind-cooling device is not used. Spectrum energy of different color light can be adjusted easily in order to show the important point of cultural relic.

Micro-ring cavity on glass fibers and molybdenum wires were fabricated. The cavities were Rh B doped organic-inorganic hybrid sol-gel films. Cavity quality factor as high as 5880 was obtained, which proves that organic-inorganic matrix are excellent materials for micro-cavity fabrication. For large cavity diameter, we observed clear whispering gallery modes that belongs to the same series. On the other hand, when cavity diameter reduced to 50 μm, higher order whispering gallery modes also appeared.

This paper proposed electrical model is based on the elastic continuum theory applied to the ferroelectric liquid crystal (FELC), which gives a good description for the simulated switching and memory behavior by the different time order and driving waveforms. Optical transmission dependence onthe complex voltage waveforms and the rotational viscosity and spontaneous polarization of cell is obtained as a function of director profile. The model agree to 10 percent experimental results, over an applied voltage of 1.0 to 20 volt. The electrical model of real FELC displays may contribute to the design and development of optimized devices.

Novel organic light-emitting diodes (OLEDs) using polymidy, fluorene-based cardo perylere polyimide (PFB5) were fabricated. EL properties of single-layer light-emitting diodes (LED) of indium-tin-oxide (ITO)/PFB5+/Al and ITO/PFB5+PBD/Al and multi-layer devices of ITO/PFB5/PBD/Al,ITO/PFB5/Alq/Al were characterized. In the pure PFB5 single layer device, the EL spectrum has a broad band and the peak wavelenght at 420nm, 450nm, and 545nm respectively. However, the EL emission fromthe single layer deviec of PFB5 blend PBD or multi-layer devices has the greatly narrow band and the peak wavelength at 545nm. Furthermore, the EL efficiency is improved significantly in these EL devices.

High-quality gallium nitride (GaN) films were prepared on Si substrates by sputtering post-annealing-reaction technique. XRD, XPS, and SAED reveal that the films consists of hexagonal wurtzite GaN wiht c-axis oriented polycrystalline grains. A strong UV photoluminescence located at 354 nm is observed for room temperature measurement. The bandgap of these films has a blueshift wiht respect to bulk GaN.

Semiconducting ferroelectric antimony sulphoiodide (SbSI) microcrystallite doped organically modified TiO₂ thin films were successfully fabricated with the sol-gel process. Ferroelectric SbSI crystallites have some attractive properties, including high dielectric permittivity, high electro-optical coefficient and high photoconductivity. SbSI is also an intrinsic semiconductor with a relatively narrow eneryg gap. The Bohr radius of the SbSI crystal was calculated larger than other semiconductors due to its large dielectric constant. If the crystal size is smaller than its Bohr radius and the microcrystallite are dispersed in a suitable matrix, a dramatic improvement of the nonlinear three-order nonlinearity will be achieved due to the quantum confinement effect. The SbSI quantum dot composites were proved to be good candidates for nonlinear and electro-optical devices. Glycidopropyltrimetroxysilane modified TiO₂ was chosen as the matrix and SbSI was synthesized in situ by using SbI₃, SC(NH₂)₂. The materials in thin film were heat-treated in different conditions and the size of the microcrystallite was characterized by the XRD. A value of 3.5pm/V of effective transverse electro-optical coefficient r_eff for the nano-composite containing 8 wt percent of antimony sulfide iodide was measured. The third-order nonlinear optical susceptibility of the SbSI quantum dot thin film was measured by degenerate four-wave mixing at 532nm using a frequency double Nd:YAG laser beams with a pulse width of around 10ns, the x⁽³⁾ value of 3 μm sample was measured to be 6 × 10^-11 esu.

Metallophthalocyanines (MPc) exhibit, among many useful properties, the abilty to protect sensors against short, intense pulse deleterious to efficient sensor operation. For the successful application of this optical limiting property, an important issue is the incorporation of MPc molecules in a matrix to fabricate a solid state system. We report here the study of different concentrations of Nickle Tetrasulfophthalocyanine (NiTSPc) encapsulated in silica xerogel matrix obtained by sol-gel technique. The resulted composites were transparent and homogeneously with appropriate optical quality. The trapping effect was check by the characteristic absorption bands of NiTSPc in the UV/Vis spectra. The optical limiting properties of the composites were measured at 532nm with 8ns pulses.

Metallophthalocyanines (MPc) have exvellent photoelectricity properties. But their low solubility in sol-gel precursor and the tendency to aggregate make it difficult to get their homogeneously composites with traditional sol-gel schedule. To overcome this problem, a newly developed 'in-situ synthesis' technique during sol-gel process is successfully used to synthesize Nicekl phthalocyanine (NiPc) in silica xerogel matrix under the irradiation of microwave. As the result, a new kind of organic/inorganic nanocomposite was obtained. The characterization of the glass sample and its extract were carried out by methods of IR and UV/VIS spectra. The 'in-situ synthesis' mechanism of NiPc and its reaction dynamics under the irradiation of microwave were discussed.

Holographic polymer dispersed liquid crystal (HPDLC) is a kind of novel photoelectronic information materials. The diffraction efficiency (DE) can be modulated by the application of electric field. HPDLC devices are potentially useful for optical communication, panel dipslay, information storage and integrated optics. The diffraction efficiency plays an important role in application of HPDLC. Based on the phase separation process of HPDLC and the morphology observed by the scanning electronic microscope (SEM), the diffractive character was studied. We investigated the dependence of diffraction efficiency on different monomers, exposure intensity, liquid crystal loading and curing temperature. The best conditions were founded to make the diffraction properites optimized and the highest diffraction efficiency 80.2 percent was gotten.

The availability of integrated optical sources in glass is expected greatly to enhance optical signal processign in glass substrates. In this paper, we report the design, fabrication and characterization of waveguide lasers in Er³⁺/Yb³⁺-codoped phosphate glass substrates. Waveguides were fabricated in a commercially avilable phosphate glass. The glass was codoped with 1.65wtpercent Er₂O₃ and 20wt percent Yb₂O₅. Waveguides were formed by K⁺-Na⁺ exchange through channel apertures etched in 150nm thick AL mask layer. Yb³⁺ is commonly used as a sensitizer in Er³⁺ lasers because it has a much larger absorption cross section near 980nm than Er³⁺, and it efficiently transfers its excited state eneryg to the upper level of the Er³⁺ 1535nm transition. The parameters that affect lasing characteristics of waveguide lasers are discussed in the light of equations for the lasing threshold and slope efficiency. Design parameters for low-threshold waveguide lasers with high slope efficiencies are described, and methods are given for substrates, waveguides and lasers cavities.

The influences of some parameters of carbon nanotube films on their electronic emission are studied in this paper. A model for the films is set up, and applied to the study. Therefore, the external electric field outside the surface, electric field enhancement factor, and optimum nanotube density of the films are explored and exprssed by analytic equations. The theoretical analyes show that the field enhancemetn factor is senstiive to nanotube denstiy, so the electron emission of the films can be improved at the specific and optimum density, and that the films composed of thinner nanotubes with small resistance should have superior emitting properties, whatever nanotube length is. The resutls obtained here are in good agreement with the relative experiments.

CdS and ZnCdS epilayers are grown on GaAs by LP-MOCVD. It is found that the thickness of CdS epilayer is greatly influenced by the growth temperature. In our case, the sticking coefficient of CdS is nearly zero at temperatures greater than or equal to 500°C. The wide values of FWHMs of CdS emission band are thought as a result of the poor crystal quality caused due to the deviation of stoichiometry ratio of Cd/S. The crystal quality can be imprved with increasing the thickness of CdS epilayers when the flow rate of H₂S is selected. The growth conditions of Zn_0.76Cd_0.24S epilayers aer investigated and the deep center emission band is attributed to sulfer-related defect.

Most ac polymer EL devices to date are based on symmetrical structure. Here novel alternating current EL devices with asymmetric structure are successfully fabricated by using a hole type polymer PDDOPV and an electron type polyer PPQ. We report that performance of polymer devices with heterojunction under ac operation is not so sensitive to thickness of the two polymer layers as udner dc operation. This new advantage of ac operation mode over dc operation mode means easy production and cheap production facility in large-scale production in the near future. DIfferent emission spectra are obtained when our ac devices are operated in ac mode, forward and reverse bias. Emission spectrum at reverse bias includes two parts; one is from PPDOPV, the other from PPQ.

Quasi-phase-matching (QMP) is an alternative approach for nonlinear optical frequency conversion compared to conventional birefringent method in the bulk crystal.In this letter 2D aperiodic optical superlattice for achieving multi-QPM is first suggested based on Fourier analysis and Stimulated annealing methods. A special optical superlattice structure containing special pre-designed values of lattice vector G that can accomplish multi-QPM process is given.

A two-step poling technique was presented for the homogenously poling of the large diameter LN wafers. Aluminum was used as the electrode material and confirmed to be suitable for the PPLN poling purpose. PPLN wafers with a homogenously poling area greater than 52 mm in diameter have been fabricated. Experimental parameters for the homogenously poling of the 3-inch LN wafer were also presented.

In the fabrication of films, substrate temperature played the most important role. It decided the phase components of the films. Quaternary component Rb_0.5Cs_0.5Ag₄I₅ thin film was grown by vacuum evaporation on NaCl crystalline substrates. A series of thin films were synthesized at different substrate temperature, and the topographical images of these films were obtained by scanning electron microscope, and their exciton spectra were measured at 80K by UV-2100 spectrophotometer. It was found that the optimal substrate temperature to grow Rb_0.5Cs_0.5Ag₄I₅ was about 340K, at other temperature, there were other complex multicomponent compounds in the films.

Field emission from a polycrystalline diamond film was observed at as low as the gate voltage of 10V by evaporation of an ultra thin metal film on diamond films as gate, and the emission image observed on a fluorescent screen shows that the electrons are emitted uniformly from the cathode area. The emission mechanisms of field emission from diamond was discussed and suggested the electron emission may be occurred from boudnaries of diamond grains.

In this work, a systematic study on the plasma-induced damage on n-type GaN by inductively coupled plasma (ICP) etching is presented. After n-contact metal formation and annealing, electrical property is evaluated by the I-V characteristics. Room temperature photoluminescence (PL) measurement of etched GaN surfaces is performed to investigate the etching damage on the optical properties of n-type GaN. Investigation of the effect of additive gas RF chuck power on these characteristics has also been carried out. The better etching conditions have been obtained based on these results.

In this article, we report the successful fabrication of high-brightness blue LEDs with InGaN/GaN multiple quantum well structures grown by low pressure metalorganic vapor phase epitaxy on sapphire substrates. The active region is composed of five pairs of InGaN well and GaN:Si barrier. The epitaxial wafer is processed into mesa diodes by inductively coupled plasma etching technique, with SiO₂ deposited by plasma-enhanced chemical vapor deposition as the etching mask. The diode chips are then encapsulated into transparent epoxy to form packaged LEDs. The typcial emitting spectrum of the blue LEDs shows a peak wavelength at 460 nm and a FWHM of 30 nm. The working voltage and output power of blue lEDs shows a peak wavelength at 460 nm and a FWHM of 30 nm. The working voltage and output power of blue LEDs at a forward current of 20 mA are 3.6V and 1.5mW, respectively. The reverse leakage current at 5V was about 5μA , and the wavelength uniformity is 0.25 nm.

We have developed a highly scattering optical transmission (HSOT) polymer, and have succeeded in applying it to a highly efficient backlight in liquid crystal displays (LCDs). In the present work, a multiple scattering modeling simulation has been developed. Also the effects of adjacent particles inside the HSOT polymer are demonstrated. Although Mie scattering theory is based on the assumption that there exists one particle, light scattering intensity profiles are extended by adjacent particles in measurement data. In order to improve the multiple scattering modeling simulation, light scattering intensity profiles calculated by Mie scattering theory are modified by using the experimental correction function. It follows that the numerical calculation improved by taking account of the adjacent particles has precisely reproduced multiple scattering phenomena inside the HSOT polymer. Based upon the results of multiple scattering analysis, an optimal design has been developed and applied to an LCD backlight system. By altering the internal particle condition, uniformity of color and brightness on the top face of the backlight can has been achieved

The photorefractive properties of low glass transition temperature (T_g) doped polymers are essentially ruled by the ability of the push-pull chromophores to align along the electric field. Therefore,a high rotational mobility is therefore needed for these non linear optical chromophores incorporated in the matrix. However, even if the influence of T_g on the photorefractive performances of guest-host polymers has been previously pointed out, this unique parameter is not sufficient to take into account the viscoelastic properties of the matrices. A complete study of the orientational dynamics of chromophores in various low T_g doped polymers, investigated by dielectric spectroscopy, second harmonic generation and electrooptical dynamical measurements, is presented. The results are fully interpreted and modeled by rheologic laws used to describe the viscoelastic behavior of polymers. Finally, the influence of the average molecular weight is also analyzed and then demonstrates the interest of using low molecular weight polymers.

Surface relief is one of the interesting properties of shape memory alloys. In this paper, we investigate the surface roughness of NiTi shape memory alloys polished in austenite and twinned martensite phases using a Wyko interferometer. The potential application of surface relief in shape memory alloys as a kind of novel micro mirror is proposed.

A novel class of organic electro-optic(EO) acceptors has been synthesized by a facile high yield synthetic route. These tricyanovinyldihydrofuran type of acceptors have been used to prepare high mb chromophores. Due to the three dimensional shape of the acceptor, these so called 'fish hook' chromophores have been proven to be highly soluble and processable by minimizing chromophore-chromophore electrostatic interactions. Preliminary EO characterization as a guest in polycarbonate film has given r₃₃ values of 70 pm/v at 1550nm for one of these chromophores. We believe this to be the highest value EO coefficient to be reported at this wavelength.

The effect of both sputtering temperature and post-annealing on the resistivity and the optical transparency of ITO films was investigated. Transparent conductive ITO films were deposited onto glass substrates using dc magnetron sputtering process with Ar pressure of 5 × 10^-3torr, power density of 5.5W/cm² and temperature ranging from 25°C to 240°C, and the ITO films were then annealed at 250°C in vacuum for 5 minutes. It was found that the sheet resistivity of the as-deposited ITO films decreased with temperature and was dominated by carrier mobility for temperature below 120°C and by the carrier concentration for temperature above 120°C. However after annealing, the lowest sheet resistivity of 1.6 × 10^-4 Ω-cm/ and the largest extent of sheet resistivity drop, presented in [ρ_s(as-grown) - ρ_s(annealed)]/ρ_s(as-grown) of 78 percent for the ITO film fabricated at 90°C were observed. The optical transmittance of as-deposited ITO films in visible light region was 76 percent and rapidly increased with temperature to up to T percent equals 88 percent at 120°C, thereafter the optical transmittance varied little with the maximum value of 90.2 percent at 200°C. However after annealing, the transmittance decreased for ITO films deposited at temperature above 120°C and increased for those above 120°C with the maximum transmittance of 89.8 percent at 90°C. This was believed due to the large reduction of defect density in ITO films for low temperature processing and to the appearance of the strong preferred orientation of (222) for high temperature deposited ITO films. The figure of merit, both F_{t c} (T%/ρ_s) and Φ_tc (T%¹⁰/ρ_s, was found to perform the best value of 14.8×10^-3 Ω^-1 and 5.5×10^-3 Ω^-1 respectively at substrate temperature of 90°C after annealing. The results suggested the optimized sputter temperature for preparing ITO films could be conducted in the moderate temperature range of 90°C rather than in high temperature if the post-annealing was introduced.

Light-emitting dendrimers are a new distinct class of material for OLEDs. Dendrimers consist of a light-emitting core, dendrons and surface groups. Dendrimers are designed for solution coating and have a number of advantages over conjugated polymers. We report our recent results for solution processed green dendrimer OLEDs. The OLEDs were fabricated by spin-coating a blend of first generation dendrimer/host material followed by the evaporation of a hole blocking layer and a LiF/Al cathode. Power efficiencies of 50 lm/W at practical brightness levels were achieved for these structures.

A new metallomesogen (MOM) was prepared aiming to the realization of liquid crystalline materials. A traditional Polymer Dispersed Liquid Crystal (PDLC) has been considered as a reference point in order to compare it with an other one obtained with the inclusion of MOM. We analyzed the thermo- and electro-optical properties of the reference PDLC and of MOM based PDLC. We focused our attention on the light transmittivity when an electric field is applied to the sample and evaluated the contrast ratio of both materials. Furthermore, a detailed morphological analysis is performed to better understand their behavior. A comparison between the PDLC with and without MOM is presented. Our experimental results demonstrated the possibility to use MOM in order to improve the transmittivity characteristic as a function of an electric field for application such as displays or windows.

The influence of various red doping materials on the photoelectric performance of highly efficient organic light emitting diodes (OLEDs) were systematically investigated. The multilayerd red-light OLEDs fabricated in this work have the structure of ITO/m-MTDATA/NPB/Alq₃:MGAg. Three different doping materials, including 4-(dicyanomethylene)-2-t-butyl-6(1,1,7,7-tetra-methyl-ljulolidyl-9-enyl)-4H-pyran, 4-Dicyanomethyl-lene-2-methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo quinoliz-in-8-yl)vinyl]4H-pyran) (DCM2), and Nile Red (NIR), were adopted. Compared with the various red-doped OLEDs, the highest luminance occureed in DCM2-doped OLED. Evidence showed that the co-existence of exciton energy transfer and carrier trapping processes in DCM2-doped OLED is the main reason leading the highest luminance occurred in that device.

An emissive hole-transporting material with a dopant was proposed for realizing highly efficient and relatively pure white-light organic light-emitting diode (OLED). The device structure included ITO/N, N'-diphenyl-N, N'-bis(1-naphthyl-phenyl)-(1, 1'-biphenyl)-4,4'-diamine (NPB)/NPB doped with 4-Dicyanomethylene-2-methyl-6-[2, 3, 6, 7-tetra-hydro-1H, 5H-behzo[ij]-quinolizin-8-yl)vinyl]-4H-pyran (DCM2) (NPB:DCM2)/bathocuproine (BCP)/tris-(8-hydroxyquinoline) aluminum (Alq₃)/Mg/Ag. By appropriately controlling the DCM2 doping concentration as well as thickness of the blue-red-emitting layer of NPB:DCM2, the white-light OLED has a relatively stable white color even the operating voltages change from 9 to 18 V.

A blue organic light-emitting diode has been made by anthracene derivative. The structure of the blue device is ITO/m-MTDATA/NPB/doped anthracene/Alq₃/Mg:Aag, where m-MTDATA, NPB and undoped Alq₃ were used for hole injection layer, hole transporting layer, and electron transporting layer, and electron tranporting layer, respectively. Three different of blue fluorescent dyes, inclduign BCzVBi, perylene, and TBPe, were introduced into anthracene as dopants for obtaining a highly luminescent blue emission. Evidence shows that the BCzVBi-doped device behaves the superior L-J and J-V characteristics due to the higher fluorescence and the formation of conducting path for carrrier transport. The emission mechanism was strongly suggestd to be due to energy transfer process from anthracene host to BCzVBi dopant and achieving a highly luminescent blue-light.

Blue organic light emitting diodes of a multi-layered strcutre were fabricated and their device performance were investigated. N, N'-bis-N, N'-diphenyl-1,1'-biphenyl-4,4'-diamine (NPB) is hole transport and blue light emitter material. We have built some multi-layer structures with hole-blocking layer (HBL). The HBL is inserted betwen the hole transport layer (HTL) and electron transport layer (ETL) to confine the charge recombination in hole-transporting layer. Three different hole-blocking materials, inclduigns BCP, TAZ, and PBD were adopted for comparison. Evidence showed that the BCP hole-blocking material possessed both the superior J-V and L-J characteristics. The superio J-V characteristics was suggested to be due to the BCP film possesign flatter surface morphology. The superior L-J characteristic was deduced to be due to the BCP possessed the smaller barrier height at NPB/BCP for electrons and/or the flatter surface morphology.

A novel model of ELectrically Controlled Birefringence (ECB) liquid crystal display was studied by detailed numerical simulation. The toothed surfaces were formed on the two substrates and the two substrates were interlaced with each other. The optimized mode with cell gap 3.4μm was determined by theoretical analysis. By using extend Jones matrix method, we have shown that the narrow viewing angle in horizontal direction, less than ±10°. The viewing angle characteristics of the novel model are compaed wiht those of usual ECB.

Color shift, viewing angle character and response speed for the in-plane switching super-twisted nematic cell are analyzed. The viewing angle depends on the change of the effective birefringence dΔn, the response time depends on the structure of liquid crystal display. The very wide viewing angle, fast resopnse times and low color shift are shown at any gray scales in this new mode. Potential applications for large screen refelctive displays are foreseeable.

Nanocrystalline SiC films have been synthesized on Si substrate using hot filament chemical vapor deposition with methane and silane as reaction gases. The microstructure, morphology and photoluminescence of the films are characterized by x-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy and photoluminescence respectively. Results show that the films deposited at relatively low substate temperature are composed of SiC nanocrystallines embedded in SiC amorphous matrix. The size of the nanocrystallites is about 5 nm. The visible-light emitting at the range of 400nm and 550nm has been observed from the nanocrystalline films at room temperature.

In this paper transition between glow-like discharge and filamentary discharge are found by gas condition being changed in dielectric barrier discharge device, discharge signal is measured by the electric methods and the current waveforms were registered by usign digital oscillography in the course of the transition. The difference between two modes is analyzed and reasons resulting in such difference are discussed.

The dynamic process of electron impact oxygen molecule in direct current electric field is simulated by using Monte Carlo method. The distribution of electron excitation and vibrational excitation collision have been obtained for range of 20 ≤ E/N ≤ 2000 Td for oxygen at atmospheric pressure of 300 K (1 Td=10^-17 Vcm²). Meanwhile, influence of electric field on excitation lighting in oxygen is also analyzed.

A special designed setup consisting tow water electrodes is used to investigate the temporal characteristic of micro-discharge in dielectric barrier discharge in Argon by the optical methods on the non-intrusive and in-situ measurement. The nonsymmetrical characteristic of the micro-discharge breakdown moment which the interval between two adjacent discharges varies between long one and short one alternately is discovered by the applied voltage increasing step by step, the influence of wall charges on the temporal behavior characteristic is analyzed at last.

High-luminance EL emissions were found to be obtainable using newly developed Mn-activated Y₂O₃-based multicomponent oxide phosphors composed of Y₂O₃ in combination with another binary compound, B₂O₃, Al₂O₃, Ga₂O₃, In₂O₃, Gd₂O₃, GeO₂ or SiO₂. The EL characteristics were investigated using a thick ceramic sheet-insulating-layer-type TFEL device. The Mn-activated Y₂O₃-based phosphor thin films were deposited by rf magnetron sputtering and postannealed. Luminances above 1000 cd/m² were obtained in TFEL devices fabricated using a ((Y₂O₃)X-(Ga₂O₃)1-X):Mn, a ((Y₂O₃)X-(Gd₂O₃)_1-X):Mn, a ((Y₂O₃)X-(Al₂O₃)_1-X):Mn or a ((Y₂O₃)_X-(GeO₂)_1-X):Mn thin film prepared with various compositions (X) and driven at 1 kHz. In particular, high luminances above 7000 cd/m² for yellow emission were obtained in 1 kHz-driven TFEL devices using a ((Y₂O₃)_0.6-(GeO₂)_0.4):Mn or a (Y₂O₃)_0.5-(Ga₂O₃)_0.5):Mn thin film prepared with a Y₂O₃ content of 60 or 50 mol.percent, respectively. In addition, high luminances above 500 cd/m² and luminous efficiencies of approximately 10 lm/W were obtained in these TFEL devices driven at 60 Hz. High-luminance multicolor emissions that changed from yellow to green could be obtained in TFEL devices using a ((Y₂O₃)_1-X-(Ga₂O₃)X):Mn thin film by increasing the Y₂O₃ content from 0 to 100 mol. percent.

In this paper, for the first time, we present a theoretical investigation of optimization and stabilization of wavelength conversion bandwidth based on a counter-propagating configuration, which correspond to second-order wavelength conversion architectures with propagation directions of signal and idler beams being opposite. Optimized example for two-, four-, six- and ten-segment chirp gratings are given, respectively. The stabilization of signal bandwidth can be realized by adjusting the pump wavelength. The numerical results show that the counter-propagating difference frequency generation (CDFG)-based wavelength converter with chirped modulation is an excellent candidate for wavelength division multiplexed (WDM) application.

The single crystals of neodymium doped lanthanum scandium borate were grown for the microchip laser fabrication. The crystal structure and parameters were analyzed to define the crystal phase and characteristics. The optical properties, such as fluorescent lifetime, refractive indices, absorption and emission spectra with doping concentration, were investigated and compared to the other neodymium doped single crystals in laser application. The fundamental lasing experiment with 808 nm, consistent with commercial diode laser wavelength, was done with Ti:sapphire laser. And we showed that the direct pumping to the level of ⁴F_3/2 make an improvement in slope efficiency and threshold when it is compared to the result of conventional pumping to the level of ⁴F_5/2 absorption band. The direct pumping played a role for reduction of dissipative heat generation in microchip laser crystal, because its quantum efficiency is higher than the conventional pumping to the level of ⁴F_5/2.

An open photoacoustic cell under heat transmission configuration has been employed to evaluate the thermal and transport properties of n-type Si doped GaAs epitaxial layer and p-type Be doped GaAs epitaxial layer grown on GaAs substrate by molecular beam epitaxial method. The variation of the characteristics of the photoacoustic signal with chopping frequency clearly indicate the different heat generation mechanisms occurring in the sample under optical excitation at 2.54eV with laser beam. The values of thermal diffusivity, diffusion coefficient, surface recombination velocity and nonradiative recombination time have been evaluated for the sample by fitting the experimentally obtained phase of the photoacoustic signal with the theoretical model. It has been observed that the nature of dopant influences the values of thermal and transport properties of the semiconductor samples.

In this paper we show that the time delay of optical pulses travelign in long fibers is influenced by the dispersion, its slope, curvature and the fiber nonlinearity. It has been shown that they have significant role on the time shift of optical pulses. In addition, nonlinear time shift of pulses that is caused by the interaction of kerr nonlinearity with dispersion have been reported.

It is required for the optical amplifier to make down sizing and also to have high efficiency to meet the demands for processing higher density of information. Especially, the film-type optical amplifier is advantageous in the field of the optical integrated circuit. From such a point, we are studying the potential materials for a waveguide-type optical amplifier with higher efficiency. The Al2O3 is possible to deposit by the vacuum deposition method using an electron beam which is excellent about the mass production. In this study, we examined about the Al₂O₃ film system as a matrix medium doped with transition elements of Cr or Co as optically active elements. These films doped with transition elements at various concentrations were characterized using absorption spectroscopy and photoluminescence (PL) et al for their optical and electrical properties. As a result, optically active films were deposited by optimizing the electron beam vacuum deposition condition. It was found that the property of the film changed from an insulator-like to a metal-like behavior at the doping rate of around 30at. percent due to the precipitation of the metallic phase of doped transition elements.

The third-order optical nonlinearity and response of polyvinyl alcohol coating films containing a cyanine dye called NK-2612 or NK-3261, were measured by the femtosecond degenerate four-wave mixing (DFWM) technique under resonant conditions. Temporal profiles of the DFWM signal were measured with a time resolution of 0.3 ps, and were found to consist of at least two components, the coherent instantaneous nonlinear response and the delayed response. It was demonstrated that the latter can be adjusted by the concentration of dye in thin films, and very fast nonlinear optical response was observed at high dye concentration. The electronic component of the effective optical nonlinear susceptibility, Iχ⁽³⁾_eI, of one of the present films was as high as ca. 1.3 × 10^-8 esu (1.8 × 10^-16 m² V^-2 in SI) at 760 nm.

Nano-porous containing photo-sensitive materials can be used in TFT-LCD color filter. It is a critical material in color filter on array(COA) manufacturing. Nano-porous material has high light transmittance, high resolution. Band low dielectric constant which can increase the aperture ratio of TFT-LCD display panel. Advantages of low exposure dose, high sensitivity and high resolution can be provided by applying cationic photo acid generator (PAG) in photo sensitive materials. In this paper, chain breakages were produced by photo chemical reaction between the tert-butyl side chain containing polymer and PAG. The butene produced from chain breakages of methacrylate polymer will become nano-porous which is critical to low dielectric constant in materials. The Montomorillonite(MMT) was use as nano-reactor. PAG were inserted between MMT layers though intercalating reaction. The d-spacing was thus increased. By measuring the changes in d-spacing with X-ray, the intercalating reaction between PAG & MMT was shown. The reaction mechanism of nano-porous formation in photo sensitive materials after UV exposure were studied with EPR. Furthermore, MTEM has been used to observe the amount of nano-porous and the hole size in order to study the interrelation among nano-porous.

It first was shown opportunity of shaping in anodic alumina substrate AlGaAs/GaAs LED chips (350x350 micron, λ_max=655 nm) with a high scale planar of radiating surface and highly of thermal dissipation and stable operation LED clusters (4x4) for information displays.

Optical second harmonic generation (SHG) from the interface of the copper tetra-tert-butyl phthalocyanine (CuttbPc) Langmuir-Blodgett (LB) film/metals has been investigated. In spite of the existence of the inversion center, the enhancement of the signal intesity for CuttbPc/Al sample was also observed. In order to clarify the enhancement mechanism, a four-layer physical model is used to explain the nonlinear optical process. It is considered that the symmetry of the CuttbPc molecule is broken by the space cahrge induced electric field. The model calculations give a good agreement with experimental results. It was shown that electrostatic phenomena at the interace is correlated closely wiht SHG signal.

To get two-dimensional (2-D) complete bandgap, a square lattice with complex crystal cell and a rectangular lattice with dielectric cylinders in air were investigated using plane wave expansion method. Their band structures were found to be different from those of an exact square lattice and they both can be implemented 2D compelte bandgaps. The rectangular lattice has compete 2D bandgaps when the ratio of the two bases is chosen properly.

The Z-scan technique is a popular method for measuring degenerate optical nonlinearities using a single laser beam. In cases where nonlinear refraction is accomplished by storing nonlinear absorption, we report an accurate analytic method for extracting nonlinear refraction from the closed aperture Z-scan transmittance curve with the aid of the open aperture Z-scan transmittance curve. This method possesses very high accurayc, especially, in the presence of strong nonlinear absorption and/or for the larger size aperture. This method is also demonstrated on a solution of Pd(mpo)₂ by the experiment.

Theoretical model of two laser beams propagating in a biased serial photovoltaic photorefractive crystal circuit is first developed and the forming conditions of three different kinds of separate spatial soliton pairs are discussed. Studies on the interaction between two solitons in one soliton pair show that only the dark soliton can affect the other, whereas the bright one cannot. The asymmetry comes from our results determined under the limit of the spatial extent of the optical beam being much less than the width of the crystal. Finally, potential application of this unilateral effect is discussed.

Two-wave coupling of focused argon laser beam with a wavelength of 514.5nm is experimentally studied in a Ce:SBN photorefractive crystal. The images of the input and output signal of the crystal are provided, which indicate that there are two-wave couplign between the interference fringes inside the crystal and the energy can transfer from one bright peak to another along the negative c-axis direction of the crystal. The fringe intesnties at the output face of the crystal are also investigated with respect to the time, the incident beam intensity ratio, and the total intensity of the incident beams. This research demonstrates a bistable state, which is significant to achieve optic-optic controlling device such as one-to-multi optic-optic switch.

Two-wave mixing properties of a Ce:KNSBN photorefractive crystal is experimentally studied while the ihcoherent erasing technique is applied. As the signal beam is with extraordinary polarization and the polarized direcitn of the pump beam has an angle φ with its extraordinarily polarized direction, the gain of the signal beam is measured with respect to the angle φ. Because of the erasing of the fanning by the ordinary component of the pump beam, the gain enhances at small angle φ and obtains its maximum at φ = 30°. The couple-wave theory with considering of the fanning effect is used to fit the experimental data and the fitting curve is coincident wiht the experimental data very well. The calculated results of the gain as a fucntin of the angle φ for different fanning factor are given out. Finally the enhancement of the gain is experimentally measured with respect to the angle between the signal beam and the normal of the crystal face. While this angle takes θ=11°, the enhancement of the gain obtains its minimum value, which means the minimum fanning.

The organic light emitting devices were investigated. The devices were fabricate dbased on the heterostructure of the hole transporter ladder-type poly (p-phenylere) and electron transporter 8-hydroxyquinoline Aluminum doped by dye pyrromethene. The experimental results have shown that the microcavity effect can be achieved by adjusting organic layer thickness. The full width at half-maximum of the electroluminescence spectra is about 26nm. This value is in good agreement with the theoretical estimation. The results were also indicated that the stability of the microcavity devices was improved as compared with the non-microcavity devices.

The transfer matrix method and the block-iterative frequency-domain method are used to calculate the point defect of 2D photonic crystals. The transmission and dispersin curves are analyzed and discuss the mechanism of increasing Q value using point defect photonic crystal as laser resonant microcavity.

The PWO crystal was grown by Cz method. We found the cause of crystal cracking was as follows: lateral crack; longitudinal length crack; along the cleaveage place crack; random fracture. Structure analysis shows that structure stress which cause the random fracture can be decreased through select high pure raw material and perfect sub-crystal, and main factor of crystal cracking is caused by thermal stress. Through a lot of experiments we have known that crystal cracking of thermal stress included not only along cleavage place crack but also lateral stratum crack and longitudinal length crack which was caused by dissimilar coefficient of expansion in all directions. During designing stable temperature field and selecting rational technology parameters and annealing process, perfect crystal was grown.

In this paper, Cz growth of silicon single crystal in a magnetic field was studied with numerical simulation method. The results of numerical simulation showed that convection of melt could be controlled when the magnetic field was added, moreover, forced convection was controlled much larger than natural convection. The oxygen concentration of the interface would decrease with the strengthening of the magnetic field intensity, but the temperature field of the melt did not change with the strenghtening of the magnetic field.

Intense two band photoluminescence (PL) at room temperature has been obtained from silicon carbide nanocrystals embedded in a SiO₂ matrix prepared by co-sputtering Si, C and SiO₂ composite targets, and subsequent high temperature annealing. Fourier transform IR spectrosocpy (FTIR) and x-ray photoelectron spectroscopy techniques were employed to analysis the structural properites of composite films. The results showed that SiC nanoparticles were incorporated into the SiO₂ matrix. PL is a consequence of the convolution of two luminescent peaks centered at about 520nm and 400nm. These emissions have been assigned to the C-rich clusters and SiC nanocrystals, respectively.

This paper presents a novel valance intersubband laser based on Si-based Si-Ge superlattice grown on a relaxed Si_1-xGe_x buffer layer. Effective mass theory is used to calculate the inplane valence subband dispersion of strain-symmetrized silicon/germanium superlattices within 4×4 Luttinger model. The valence band offsets and strain parameters are calculated by Van de Walle's model-solid theory. Analysis of the in-plane energy dispersion shows that the light-hole effective mass is inverted in the k-space region. The laser structure can be desigend with a simple quantum cascade scheme. Our calculation shows that with the electrical pump, it is possible to achieve population inversion between the two subbands in local k space where the light-hole effective mass is inverted. Optical gain of the order 100/cm can be achieved wiht a pumping current density 10KA/cm².

In this work, the reason of flat interface crystal growth was analyzed and rational technological parameters were desigend and high quality sodium bismuth tungstate single crystal of 45mm in diameter and 35mm in length was grown by Czochralski method. X-ray diffraction spectra showed that the NBW single crystal had cubic system and the space group was I₄₁/a; Transmission spectra of NBW indicated that its anti-radiation damaging capability was strong; Its emission spectra analysis showed that the emission peak was in the range of visible light--green light wave band.

In this work, YVO₄ crystal with excellent property was grown by Czochralski method when rational growing parameters were designed; the result of TG-DTA analysis showed that the thermal stability of YVO₄ crystal was good, and the result of IR spectrum testing showed that YVO₄ crystal was a kind of crystal with wide transparence area and good optical property.

ZnO films were deposited on sapphire, Si, quartz and Cornign 7059 glass substrates by r.f. sputtering. A 356 nm UV photoluminescence (PL) peak corresponding to inter-band transition was observed for the films deposited on sapphire, Si and quartz substrates when excited with 270 nm light. For the films prepared on Corning 7059 glass, only a 446 nm blue emission peak originated from electron transition from shallow donor level of oxygen vacancies to the valence band was found. After high temperature annealing in air, the intensity of PL peaks for the films onthe former three types substrates increased pronouncedly.

This paper presents some results on the nonlinear output charactertistics and critical behaviors of a nonlinear optical system with conjugate polymer like polydiacetylenes, in a three-level model. Based on the model of interaction of this kind of matter with the pumping field, probing field and coherent field, the nonlinear susceptibility deduced by the method of the density matrix element, and the multistable output characteristics and effects of lasing or lasing wihtout inversion are furthe studied, using the dynamic equation of the 'forced oscillation model of laser and bistability'. On the other hand, through the approach of 'quasi-thermal dynamics', we analyzed the properites of the critical point of the system. The result shows that when the system is set on a tri-stable situation there exist an unstable critical point of second kind phase transiton and near which the behavior of the system had not been reported before, as we know.

In this paper we report the preparation of glass ceramic based on PbF₂GeO₂WO₃SiO₂BaF₂ system co-doped Yb³⁺/Ho³⁺ rare-earth ions. We prepare the upconversion luminescence glass ceramic sample by investigating prepartion process parameter of this system and selecting doping concentration. In our experiment optimum proportion of Yb³⁺/Ho³⁺ rare-earth ion concentration is 6:1. We observe the excitation spectrum by using Japanese Hatachi F4500 fluorescent photometer whose exciting light is 980nm semiconductor laser. There is a strong emission peak at 545nm. By analyzing rare-earth ion energy level and spectral character, we build up the upconversion luminescence mechanical model of this system. This sample has many advantages such as simple preparation process, big dimension, good chemical stability, high mechanical robustness and broad excitation band. It is worth of further research.

In this paper through the fusion method we prepare the sample based on 45PbF₂45GeO₂10WO₃ host glass co-doped Yb³⁺/Er³⁺ rare-earth ions. During the preparation glass annealing temperature is 380° and constant temperature time lasts over 4 hours. Through the V-prism we find that refractive index of host glass is 1.517 and that of this sample is approximately 1.65. At the same tiem we observe the transmissivity by using the UV-visible-IR spectrography during the wavelength range from 0.35 to 2.5μm. The transmissivity of host glass is beyond 73 percent. That of the sample is beyond 50 percent and there are characteristic absorption peaks of rare-earth ions. Moreover we observe the excitation spectrum by using Japanese Hitachi F4500 fluorescent photometer whose pump light is 980nm semiconductor laser. There are a strong emission peak at 550nm and a weak peak at 680nm. Finally through the discussion and analyiss we point out new reserach and development of upconversion luminescence glass.

SrAl₂O₄:Eu²⁺,Dy³⁺ was synthesized from various composition by high-temperature solid-state reaction and the effect of composition on the afterglow phosphorescence have been evaluated. The luminescent propertis were depended to a large extent on the calcination conditison and stoichiometry under which the phosphor is prepared. In order to study the luminscent character of the long-afterglow material, the whole decay curves of 10h were measured. The emission spectra and the excitation spectra of SrAl₂O₄:Eu³⁺,Dy³⁺ powders were shown, and the poweder x-ray diffraction pattern was obtained also.

By changing the ratio of Al:Sr, we get a new type phosphor SeAl₃O₅(OH):Eu²⁺,Dy³⁺ emitting blue light with the afterglow characteristics of over 10 hours. The emitting peak is at 484nm, which is corresponding to the spectral transition 4f5d of Eu²⁺. The influence of different temperatures and different fluex on the luminescent properties of SrAl₃O₅(OH):Eu²⁺,Dy³⁺ was studied. The results indicate that increasing the sintering temperature helps crystal to grow, and that the luminescent properties of SrAl₃O₅(OH):Eu²⁺,Dy³⁺ is improved by higher temperature or the flux especially H₃BO₃, which increases the initial brightness and prolongs the afterglow time comparing with the SrAl₃O₅(OH):Eu²⁺,Dy³⁺ that without additives.

A strong photoluminescence (PL) band has been observed at room temperature from ZnO films grown by r.f. sputtering when excited with 340-398 nm light. The PL spectrum consists of three bands with wavelengths 420 nm, 446 nm, and 490 nm, respectivley. The violet peak originates from the electron transition from the shallow level of interface trap at the grain boundaries to the valence band, the blue peak is due to the electron transition from the shallow donor level of oxygen vacancies band and the green emission is attributed to the electron transition from ionized oxygen vacancies to valence band.

This paper presents the UV photoconductivity properties of GaN films doped with different Mg concentrations deposited by MOCVD. It was observed that for the undoped and weakly doped GaN films the UV photocurrent response was relatively large and the realx time was relatively short. With an increase in doped Mg content, the samples became P type, the photocurrent response become weak and the realx time became long.

Laser identification of friend or foe system use laser wave radiated by high-power semiconductor laser as carrier wave for transmitting signal, and it is cooperative system which is carrying wave can return. The modulating return wave of the system uses reflection prism are stable, when the detectors of all-oriented photoelectric receiver detect the key-code of identification of friend or foe, electrical machinery will drive the reflecting prism to revolve in order to form modulating return wave. To inspect reliable return wave signal and solve strong background lights disturb as well as adapts to changeable detecting technique problem of APD photo-electric detector, the system adopts obscure noise compensation and signal identification technique controlled by computer in APD photo-electric system.

In this paper, we prepared SrAl₂O₄:Eu²⁺,Dy³⁺ long persistence phosphorescence enamel coatings by using SrAl₂O₄:Eu²⁺,Dy³⁺ phosphor powders and glass frits and organic vehicle. The glass frits were specially prepared to fit the SrAl₂O₄:Eu²⁺,Dy³⁺. The prepared phosphorescence enamels were found to have very bright long lasting phosphorescence after being excited by the ordinary fluorescent lamp or sunlight. The emission can be seen even 12h after removal of the exciting soruce. The emission shows a broad band peaking at 520nm resulted from the transition of 4f-5d of Eu²⁺ ions in SrAl₂O₄:Eu²⁺,Dy³⁺. The phosphorescence enamels can be used as energy saving display in various applications.

In this paper, rare earth europium ion doped SrO-B₂O₃-Al₂O₃-SiO₂ glasses were prepared. The batches were melted under an ambient atmosphere and reheated under a reducing atmosphere. The glass after being reheated in the reducing atmosphere show long after glow phosphorescence resulted from 5d-4f transition of Eu²⁺ ion . Whereas the glasses melted under an ambient atmosphere show luminscence peaks attributed to the ⁵D_i→⁷F_j of Eu³⁺ ion.

The stress distribution in silica optical waveguides on silicon is calculated by using finite element method (FEM). The waveguides are mainly subjected to compressive stress along the x direction and the z direction, and it is accumulated near the interfaces between the core and cladding layers. The shift of central wavelegnth of silica arrayed waveguide grating on silicon-substrate with the designed wavelength and the polarization dependence are caused by the stress in the silica waveguides.

We found that the monomers with vinyl groups at two ends of the main chain after exposed to linearly polarized UV light can induce homogeneous alignment of liquid crystal molecules. The monomer films were coated on the surface of indium tin oxide glass substrates and then direclty illuminated by LPUV. UV-visible spectra elucidated high photochemical reaction degree obviously. The petilt angle of liquid crystal was 0.8 degree. Good electro-optic characteristics of TN-LCDs were obtained and multi-domain mode was fabricated using these photo-alignment materials.