Terahertz (1 - 10 THz) quantum-well photodetectors and quantum- cascade lasers have been investigated. The design and projected detector performance are presented together with experimental results on several test devices, all working at photon energies below the optical phonons. Background limited infrared performance (BLIP) operations were observed for all samples (three in total) designed for different wavelengths. For lasers, a set of THz quantumcascade lasers with identical device parameters except for the doping concentration has been studied. The δ-doping density for each period was varied from 3.2 × 10¹⁰ to 4.8 × 10¹⁰ cm^-2. We observed that the lasing threshold current increased monotonically with doping. Moreover, the measured results on devices with different cavity lengths provided evidence that the free carrier absorption caused waveguide loss also increased monotonically. Interestingly however, the observed maximum lasing temperature displayed an optimum at a doping density of 3.6 × 10¹⁰ cm^-2.

We report a photoluminescence observation of robust excitonic polarons due to strong coupling of exciton and longitudinal optical (LO) phonon as well as Fano-type interference in high quality ZnO crystal. At low enough temperatures, the strong coupling of excitons and LO phonons leads to not only traditional Stokes lines (SLs) but also up to second-order anti-Stokes lines (ASLs) besides the zero-phonon line (ZPL). The SLs and ASLs are found to be not mirror symmetric with respect to the ZPL, strongly suggesting that they are from different coupling states of exciton and phonons. It is more interesting that a new group of peaks, including a ZPL and several SLs, are observed. The observations can be explained with a newly developed theory in which this group is attributed to the ground excitonic polaron state and the other group is from the excited polaron states with LO phonon components partially decaying into environal phonon modes. Besides these spectral features showing the quasiparticle properties of exciton-phonon coupling system, the first-order SL is found to exhibit characteristic Fano lineshape, caused by quantum interference between the LO components of excitonic polarons and the environal phonons. These findings lead to a new insight into fundamental effects of exciton-phonon interaction.

In dielectric spheres light can be guided through high-Q whispering- gallery-modes (WGMs) with an unique combination of strong temporal and spatial confinement of light. Glass microspheres are then of interest for a large number of applications including compact lasers sources and biological sensing. Here we first review some basics of spherical resonators and we then focus our attention on these two applications. We describe the fabrication of both the microspheres and the tapered fibers and we demonstrate efficient coupling of light from the tapered fiber to the microspheres. We report some results on WGM microlasers in different types of erbium-doped glasses and finally a brief overview of the state of the art of microspherical biological sensors is presented.

Quantum dots, with functional group on surfaces, can be attached to bio-molecules to form quantum-dots/bio-molecule complex. With their excellent photo-electronic properties, quantum dots are now widely used to label the bio-molecules and highlight a cell's nucleus and microtubule fibers. They may also be used to control and operate the bio-molecules. We investigate the synthesis of the CdSe/ZnS core- shell quantum dots. To make the quantum dots water-soluble, the TOPO, TOPSe, and HAD ligands on the surface of CdSe/ZnS QDs were replaced by mercaptoundecanoic acid (MUA). The MUA-coated quantum dots are dispersible in water. For the use in biology, it is required that the quantum dots, when surrounded by a bio-environment, have high quantum yield and long fluorescence lifetime. Our study indicates that quantum yield of the core-shell quantum dots exceeds 60% and fluorescence lifetime of the electrons in the excited state is around 20 nano seconds. The CdSe/ZnS core/shell structure is very stable. No significant fluorescence decay is observed with a prolong excitation by a 365 nm ultro-violet light source of 30 mW. Here the function of the ZnS is two-fold: as both the barrier and the passivation layer for the CdSe quantum dots. In addition, the S^-2 bonds are bio-active, which form stable bonding to bio-molecules.

According to the incident angle domain, the design of an ultraviolet omnidirectional reflector deposited on substrate of quartz glass is briefly presented. The spectral wavelength region of the design is from 328.95nm to 352.11nm and the relative bandwidth is 6.80% in theory. An experiment has been done to verify the design by using HfO₂ and SiO₂. The experimental result shows that the band gap corresponds to wavelength band from 331.2nm to 350.4nm and the relative bandwidth is 5.63%.

Aluminophosphate AlPO₄-5 single crystal is a kind of nanoporous material. Its framework consists of alternative tetrahedra of AlO₄ and PO₄ which form an array of opened one-dimensional channels and pack in hexagonal structure as two-dimensional photonic crystal. The inner diameter of the channel is 0.73 nm. Since the AlPO₄-5 single crystal is electrically insulated and thermally stable up to 900°C, it is an ideal host to incorporate nano-structured species. These guest-host materials are potentially new functional materials in electric transport, optic switches, nonlinear optics and lasers. We have synthesized two different types of guest-host systems, including selenium and carbon nanotube in the channels of AlPO₄-5 crystals. Polarized absorption spectra and polarized Raman spectra have been investigated. Both crystals behave as good polarizers with high absorption for the light polarized parallel to the c-axis of the crystal. This anisotropic optical property implies that ordered species with a large aspect ratio are formed in the channel. The polarization angle dependence of the Raman intensity indicates that the enclosed species are highly oriented in the channels with their dipole transition moment mostly along the channels. These guest-host systems are useful for applications of optical filters or polarizers.

With the deep research of measurement for microscopic or nanometer level scale at present the concept of Critical Dimension(CD) is pointed out in many papers^[1,4,], they always include some analyses of measuring uncertainty for current technology of measurement, but our new idea or definition for geometrical action scale (GAS) is the limited scale or uncertainty of measurement in microscope that we can approach to for the most advanced method, technology, set-up or instrument, for example: The modern interferometer, SPM^[5] and other various scattering experiments using the beam of microscopic particles. It would be found that the research included fundamentals for microscopic particle geometric scale is not easy to explore, some reasons perhaps are affected by which the classical quantum mechanics study of matter usually start from energy or energy level not from geometrical scale and by the Heisenberg relation of measuring uncertainty. Our work just wants to research on these fundamentals in physics for microscopic particles geometric scale. At first, a new physical quantity relative to microscopic particle geometric scale is directly suggested in this paper, it also may be deduced from the completeness of units system or dimension system refer to optics principles or quantum optics principles. We find that the wavelength of Louis de Broglie matter wave is either the length dimension or relative to the geometric scale of microscopic particles, and we define it as the geometrical action scale (GAS) of microscopic particles. The significance of the geometrical scale of microscopic particles or GAS in physics is discussed.

The artificial colloidal crystal with the three-dimensional periodic structure was prepared through the self-assembly of silica microspheres in the cell. Silver is assembled into the voids of the colloidal crystal by an electrochemical reduction of Ag⁺ in aqueous solution. The position of the stop band could be tuned by controlling the ratio of Ag/silica.

We used a chemical method to synthesize three kinds of PbS nano-particles. There were different spatial forms in the nano-particles. The part of them were nano-ribbons with different length in shape, other parts were in nano-particles. We measured the nonlinear optical performance of suspension of three kinds of PbS nanoparticles, including nano-ribbons, nano-particles, in ethanol by nonlinear transmission and Z-scan technique with a doubled frequency Nd:YAG laser at 532nm. It was found that the PbS nanoparticles with various spatial structures exhibit good optical limiting performances. The maximum nonlinear refractive index is about 6.96x10^-4 cm²/GW, nonlinear absorption coefficient is about 6.98cm./GW.

Optical silica nanowires fabricated using a taper-drawing approach exhibit extraordinary uniformity, making them suitable for low-loss optical wave guiding. Air-clad optical nanowires can be used as subwavelength-diameter single-mode waveguides from the ultraviolet to the near-infrared spectral range. Using these nanowires as building blocks we assembled photonic devices that are much smaller than comparable existing devices, indicating the great potential for developing micro- and nanoscale photonic devices for future applications in a variety of fields such as optical communication, optical sensing and high-density optical integration.

Self-organized vertical ordering in self-assembled quantum dot superlattices is based on the long-range elastic interactions between growing dots on the surface and those buried in the previous superlattice layers. These interactions may lead to a corrected dot nucleation and to the formation of ordered superstrsuctures. In this paper, we present a systematic investigation of the strain distribution of self-organized lens-shaped quantum dot for the case of growth direction on (001) substrate. The three-dimension finite element analysis for an array of dots is used for the strain calculation. The dependences of the strain energy density distribution on the thickness of capping layer are investigated in detail when the elastic characteristics of the matrix material are anisotropic. It is showed that the elastic anisotropic greatly influences the stress, strain and strain energy density in the quantum dot structures. The anisotropic ratio of the matrix material and the combination with different thickness of the capping layer may lead different strain energy density minimum on the capping layer surface, which can result in various vertical ordering phenomena for the next layer of quantum dots, they are partial alignment, random alignment and complete alignment.

The photochromic diarylethene, 1, 2-bis(2-methyl-5-(3-trifluorophenyl)-3-thienyl)perfluorocyclopentene (BMTTP), was synthesized. This compound undergoes a photochromic reaction either in solution, PMMA amorphous film or in the single crystalline phase. Using this compound as recording medium, two-photon optical bit pattern storage was performed successfully by a femtosecond laser and a reflection confocal scanning-fluorescence microscope.

Yttria Stabilized Zirconia (YSZ) and Silicon Carbide (SiC) nanolayers were deposited on several substrates using a Magnetron Sputtering system with YSZ and SiC targets. The combined effects of pressure and RF-DC power and post-annealing with CO₂ laser irradiation on the thin film microstructure was investigated by Infrared Spectroscopy (IR), Atomic Force Microscopy (AFM), X-Ray Photoelectron Spectroscopy (XPS), and Lateral Force Microscopy (LFM). It has been found that the microstructure and optical properties of these materials can be controlled by laser power and irradiation time. Furthermore, shorter annealing times were needed as compared with conventional annealing procedures, results indicate that this processes could be used to produce suitable nanolayers for industrial applications.

Silicon Rich Oxide (SRO) has luminescent properties that can be used in silicon optoelectronics devices. Nowadays the emission mechanisms are not completely understood, leading to a high potential field of research. The study of the SRO characteristics and its relation with the emission would provide information on the mechanism of radiation. In this work the optical properties of SRO are studied. Photoluminescence (PL), transmittance and refractive index of silicon rich oxide films annealed at high temperature during different times have been obtained. PL spectra show a considerable emission of visible light with different thermal treatment times and have a wide wavelength spectrum from 400 to 600 nm (3.1-2 eV ) and 650 to 850 nm (1.9-1.45 eV). Absorption spectra were studied and the optical band gap was determined. It can be seen that the optical band gap determined from these spectra changes as the silicon excess varies. The refractive index of SRO films also augments with the excess of silicon, and with the thermal treatments time.

Nanopore arrays were fabricated by self-organized anodization on aluminum. A two step anodization process was used to oxidize aluminum in H₂SO₄ solution. Hexagonally ordered pore array films were obtained by dissolving the remained aluminum base of anodic alumina in saturated HgCl₂ solution. Scanning electron microscopy and X-ray Diffraction were used to investigate the morphology and crystal structures of the porous anodic alumina films. An investigation was made on the optical transmission, optical absorption and photoluminescence of the porous anodic alumina films. The results show that the highly ordered anodic porous alumina films are amorphous. The transmission spectra and absorption spectra of porous anodic alumina films abruptly curve at wavelength of 360nm, the optical transmission increases at wavelength more than 360nm, the optical absorption increases at wavelength less than 360nm. The photoluminescence intensity and peak position of the porous anodic alumina films depend strongly on the excitation wavelength, there is a wide blue photoluminescence band in the wavelength range of 340- 600nm.

High quality ZnO films have been successfully grown on Si(100) substrates by Metal-organic chemical vapor deposition (MOCVD) technique. The optimization of growth conditions (II-VI ratio, growth temperature, etc) and the effects of film thickness and thermal treatment on ZnO films' crystal quality, surface morphology and optical properties were investigated using X-ray diffraction (XRD), atomic force microscopy (AFM), and photoluminescence (PL) spectrum, respectively. The XRD patterns of the films grown at the optimized temperature (300°C) show only a sharp peak at about 34.4° corresponding to the (0002) peak of hexagonal ZnO, and the FWHM was lower than 0.4°. We find that under the optimized growth conditions, the increase of the ZnO films' thickness cannot improve their structural and optical properties. We suggest that if the film's thickness exceeds an optimum value, the crystal quality will be degraded due to the large differences of lattice constant and thermal expansion coefficient between Si and ZnO. In PL analysis, samples all displayed only ultraviolet emission peaks and no observable deep-level emission, which indicated high-quality ZnO films obtained. Thermal treatments were performed in oxygen and nitrogen atmosphere, respectively. Through the analysis of PL spectra, we found that ZnO films annealing in oxygen have the strongest intensity and the low FWHM of 10.44nm(106 meV) which is smaller than other reported values on ZnO films grown by MOCVD.

Titanium nitride films are deposited on AISI 304 steel with a hollow-cathode-discharge (HCD) ion-plating technique. The status of residual stresses in TiN thin film coated on AISI304 substrate by HCD is studied by x-ray diffraction stress analyzer. By analyzing morphology of the residual stress of TiN thin film at interface between TiN film and AISI 304 substrate, the adhering mechanism of TiN thin film is understood as follows: the mechanical interlocking had important contribution to the adhesion strength, the thermal stress is the major factor which resulting TiN thin film peeling off spontaneously. The results show that the value of thin film is -210MPa~-650Mpa, and the thermal stress is compressive, the intrinsic stress is tensile, origins of the residual stress are primarily discussed.

Nano-sized amorphous silicon embedded in SiNx films are prepared by helicon wave plasma-enhanced chemical vapor deposition technique (HWP-CVD), and Si nanocrystals embedded in SiN_x films is obtained after furnace annealing (FA) in nitrogen ambient. The structure and optical properties of nano-sized amorphous and crystalline silicon embedded in silicon nitride (SiN_x) thin film is comparatively analyzed. Raman scattering measurement shows that, apart from appearance of a new peak at about 496-510cm^-1 corresponding to Si nanocrystals scattering, the relative scattering intensity of the two peaks located at 150 cm^-1 and at 480cm^-1 increases after high temperature annealing, indicating that the microstructures of the annealed films becomes more disordered. Meanwhile, the photothermal deflection spectra (PDS) show the optical absorption coefficient of annealed samples in the band gap increases in about one order of magnitude, indicating that more gap states exist in the annealed samples. After further annealing in forming gas and comparing the PL results of both as-deposited and thermal treatment thin film, it is found that red shift of the main peak of PL spectra is correlated with the enlarge of the silicon size. The role of interface states between silicon clusters and SiN_x matrix influence the PL behavior is discussed.

Diamond-like carbon, as anti-reflective and protective films, are prepared on silicon lens with φ150mm diameter. The measurement results show that uniformity error is less than 3% at range of φ150mm, the peak transmittance value is near to theory value, the films have excellent wear-resistance. Films' surface roughness is less than 10 nanometer from the atomic force microscopy image.

In this paper, the diamond-like carbon (DLC) film is deposited by pulsed vacuum arc ion source. A great lot of technical experiments are done with various technique parameters, including main loop voltage, pulse frequency, ion source structure and size, substrate height and magnetic intensity, for finding out the influence of technical parameters on film uniformity. Meantime, a handy film thickness measurement instrument is used to measure the distribution of film thickness. Finally, the influences of technique parameters on film uniformity are achieved.

Surface wave-sustained plasma (SWP) is one of the low-pressure, high- density plasma. Applying this technique, diamond-like carbon (DLC) films with excellent characteristics can be prepared by physical vapor deposition (PVD) method. However, the films' application is restricted in some degree, because it is difficult to control the film properties. In this paper, SWP was excited along a conductive rod at a frequency of 2.45 GHz without magnetic fields around the chamber wall. The fundamental theories of plasma diagnostic were presented and plasma properties were studied with a Langmuir probe under the conditions of depositing DLC films by PVD method with a graphite target. Plasma density, electron temperature, plasma potential and target current were measured at difference technique parameters such as gas pressure, microwave power, and so on. As a result, it was proved that plasma properties are greatly affected by microwave power, target voltage and argon gas pressure in chamber. The gas mass flow rate had almost no effect on plasma characters. At the same time, the results indicated that electron density is up to 10¹¹-10¹²cm^-3 even at the low pressure of 1 Pa.

ZnCdSe thin films were potentio-statically electrodeposited on tin oxide coated conducting substrates using an aqueous acidic bath. The growth conditions were optimized by the cyclic voltametric study. This study shows that alteration of the bath conditions yields any desired composition of this material. The role of the concentration of the various species present was discussed from optical transmittance measurements. It is observed that the concentration of the Cd ion plays a key role in forming the ternary ZnCdSe system. Besides, the initial low concentration of the non-metallic ions is also an essential condition for the alloy formation. The nitrogen ion implantation study indicated a reduction of the sample resistance and a partial annealing effect. The electro-synthesized ZnCdSe thin films were studied by structural, morphological, optical, and transport properties before and after nitrogen ion implantation of various dosage.

Raman scattering is an inelastic process, in which we can obtain information about material lattice vibration frequencies. If the wavelength of the excitation laser is within the electronic spectrum of the material, the intensity of some Raman-active vibrations will increase enormously. This resonant Raman effect can be quite useful to explore the electron-phonon coupling in the substance. In this article, we report the investigations on the electron-phonon coupling effect in Se nanoclusters using resonant Raman technique. Up to 10 different laser lines are used in the experiment. The Raman intensity strongly depends on the energy of the laser lines used for excitation. The one-phonon symmetric A₁ modes for Se single helix and Se₈ rings are enhanced in the vicinity of their absorption bands. Detailed analysis shows that the Raman intensity in the high frequency range 450 - 550 cm^-1 is a sum of individual second-order Raman scattering intensities for the confined Se species. These two-phonon Raman shifts occur at twice the frequency shift of the first-order Raman lines, and their intensities are also enhanced when the excitation laser energy matches an electronic transition in Se nanoclusters.

CdS nanocrystalline were prepared by precipitation from a mixture of aqueous solutions of cadmium salts and sulfur salts without adding any surface-termination agent. Their crystal structures and particle sizes were determined by X-ray diffraction (XRD). The CdS nanocrystalline precipitated from different precursors exhibited three cases: cubic phase, hexagonal phase and a mixture of cubic and hexagonal phases. The photoluminescence (PL) of cadmium salt precursors and CdS nanocrystalline is also analyzed. Similar spectral band structure of cadmium salt precursors and CdS nanocrystalline is found. The spectral intensity of the CdS-Cd rich and CdS-S rich nanocrystalline shows that the precursors themselves have important effect on the PL of CdS nanocrystalline.

Hydrogen-free diamond-like carbon (DLC) films were deposited by a new-type surface wave-sustained plasma physical vapor deposition (SWP-PVD) system under various technique conditions. Electron density was measured by a Langmuir probe, while the film thickness and hardness were characterized using a surface profilometer and a nanoindenter, respectively. Surface morphology was investigated by an atomic force microscope (AFM). It was found that the electron density and deposition rate increased following the increase in microwave power, target voltage, or gas pressure. The typical electron density and deposition rate were about 1.87-2.04×10¹¹ cm^-3 and 1.61-14.32 nm/min respectively. AFM images indicated that the grains of films changes as the technique parameters vary. The optical constants, refractive index n and extinction coefficient k, were obtained using an optical ellipsometry. With the increase in microwave power from 150 to 270 W, the extinction coefficient of DLC films increased from 0.05 to 0.27 while the refractive index decreased from 2.31 to 2.18.

In He, Ne or Ar gas under a deposition pressure of 10Pa, nanocrystalline silicon films were prepared by pulsed laser ablation, which the deposition time was 5, 7, 13, 15, 69 and 350min, respectively. A Lambda Pyhsik XeCl excimer laser (wavelength 308nm, pulse duration 15ns, laser fluence 4J/cm², repetition rate 1Hz) was used, and the distance between Si target and the substrate was 3cm. The Raman spectra indicate that the films are nanocrystalline. Scanning electron microscopy images show that the discrete nanoparticles are first formed, more and more nanoparticles are obtained with increasing of deposition time, and then some nanoparticles start to aggregate and form continuous film, and finally the film ruptures due to the stress. It is the complicated interaction between nanoparticles as-formed in the film and those produced subsequently to lead to the phenomena mentioned above. The morphology of the films deposited in different ambient gases is compared. The result shows that aggregation between nanoparticles, film-formation and rupture take place in a lighter gas earlier than those in a heavier gas. This is related to the different growing rate of the films deposited in different gases.

In this paper, we prepared carbon doped nanocrystalline ZnO by pyrolyzed zinc stearate at 250°C and 300°C respectively. The XRD curves indicate the sample has polycrystalline hexagonal wurtzite structure. The XRD data of the sample prepared at 250°C and 300°C has a bigger angle shift about 0.05°and 0.3°respectively. That indicate the structure of the sample has some changes. The EDS indicate the sample contains Zn, O and C. So the XRD shift may attribute to the C. The XPS indicate the C doped in the crystal lattice of ZnO of the sample prepared at 300°C, and the sample prepared at 250°C may be only a few of C doped in the crystal lattice of ZnO. The PL of the sample prepared at 300°C only has a weak ultraviolet emission, which indicates C modified the nanocrystalline ZnO surface as a non-radiative recombination center. In this process C could non-radiatively recombine the carries on the nanocrystallin ZnO surface. The sample prepared at 250°C has a strong visible emission at about 530 nm. This emission band could be attributed to oxygen vacancy because C schlepped some oxygen on the nanocrystalline ZnO surface.

Oxidizing thick porous silicon layer into silicon dioxide is a timesaving and low-cost process for producing thick silicon dioxide layer used in silicon-based optical waveguide devices. The solution of H₂O₂ is proposed to post-treat thick porous silicon (PS) films. The prepared PS layer as the cathode is applied about 10mA/cm² current in mixture of ethanol, HF, and H₂O₂ solutions, in order to improve the stability and the smoothness of the surface. With the low-temperature dry-O₂ pre-oxidizations and high-temperature wet O₂ oxidizations process, a high-quality SiO₂ 30 μm thickness layer that fit for the optical waveguide device was prepared. The SEM images show significant improved smoothness on the surface of oxidized PS thick films, the SiO₂ film has a stable and uniformity reflex index that measured by the prism coupler, the uniformity of the reflex index in different place of the wafer is about 0.0003.

The paper reports that InP epitaxial layers were grown on iron doped semi-insulating GaAs substrate by low-pressure metalorganic chemical vapor decomposition (LP-MOCVD). Prior to the growth of InP, amorphous InP buffer layer was grown at 400°C, then the substrate zone temperature was raised to the normal InP growth temperature and InP epitaxial layer was grown at 665°C. The obtained InP layers have been characterized by transmission electron microscope, optical microscope, X-ray diffraction, photoluminescence measurement.

Sodium bismuth titanate (Na_0.5Bi_0.5TiO₃, NBT) is considered to be an excellent candidate for a lead-free piezoelectric material from the viewpoint of environmental protection. The optimum temperature of crystallinity is 650°C. The films exhibit a well-defined hysteresis loop with a remnant polarization 2Pr of about 1 μC/cm² and a coercive voltage V_c of approximately 0.9V. The films also show good insulating property at room temperature. The high frequency C-V curve is indicative of good film/substrate interface characteristic. The fixed charge density (N_fc) and the surface state density (N_ss) are considered to be adequate for a ferroelectric field effect transistor operation. Electrical measurements results show that this kind of films have a potential practice for device applications such as memory and switching devices.

Single layers of MgF2 were deposited upon super polished fused-silica substrates by resistance boat evaporation at different temperatures. The transmittance and reflectance spectra were measured and the optical losses were analyzed. The laser-induced damage thresholds (LIDT) were characterized at the wavelength of 355nm for certain samples. The absorbance of the samples was discussed related to the LIDT. The increasing absorbance with the higher deposited temperature was attributed to the decreasing of the LIDT. And the high micro-defect density of the sample surface resulted in the low LIDT.

ZnO nanoparticles had been successfully prepared by annealing the precursors at different temperature, which were produced by the chemical precipitation method. The annealing temperature is a key parameter to prepare ZnO nanoparticles. The microstructure of the resultant nanoparticles was studied by means of XRD, TEM and PL spectra. The ultra-violet emission as observed at room temperature.

Strong room temperature ultraviolet emission is observed in highly oriented ZnO microcrystallite films prepared on (001) sapphire substrates by pulsed laser deposition method (PLD). The influences of substrate temperature, distance between the target and the substrate, oxygen pressure, and laser energy density on structural and optical properties were systemically studied by x-ray diffraction (XRD), scanning electron microscopy (SEM) and room temperature photoluminescence (PL) measurements. The XRD as well as the SEM results showed that all the four experiment parameters had obvious effects on the structure and micrograph of the derived ZnO films. From the room temperature photoluminescence spectra, all the derived samples have a strong ultraviolet (UV) emission about 376nm, and the visible emission is depressed greatly. Additionally, the results showed that the processing parameters could obviously affect the PL properties and the reasons were also discussed. From our results, the UV PL intensity is strongly depending both on the crystallinity and the stoichiometry of the ZnO films.

Silicon carbide thin films are prepared by helicon wave plasma enhanced chemical vapor deposition (HW-PECVD) using a gas mixture of silane, methane, and hydrogen at a constant gas flow ratio under varying negative DC bias voltage. The structural and optical properties of the deposited films are investigated using Fourier transform infrared spectra (FTIR), ultraviolet-visible (UV-VIS) transmission spectra, and scanning electron microscopy (SEM). It is found that by applying the moderate bias on the substrates to accelerate the energetic ions, nanocrystalline silicon carbide can be deposited at lower onset temperature than without bias, and the crystalline grain size of the films is smaller and more uniform. The mechanism about the enhancing effect of the bias is discussed on the performance of positive ions in the plasma.

GeTe/Sb₂Te₃ superlattice-like (SLL) structure, consisting of alternating thin layers of two different phase-change materials, GeTe and Sb₂Te₃, were grown by magnetron sputtering technique on silicon (100) and polycarbonate substrates. The optical and thermal properties as well as the structural characterization of the film were investigated. Ellipsometric spectroscopy showed that the optical constants could be modulated by changing the ratio and period of the SLL structure in the range of 400 to 800 nm. Differential scanning calorimeter (DSC) measurements indicated SLL structure to have lower activation energy than that of the mGeTe-nSb₂Te₃ pseudobinary with the same ratio. X-ray diffraction (XRD) analysis shows that Ge₂Sb₂Te₅ was formed at the GeTe/Sb₂Te₃ interface after laser-induced crystallization.

Two novel photochromic dithienylethenes, [1-(2-methyl-5-p- methylphenyl-thien-3-yl)-2-(2-methyl-5(4-(1,3-dioxolane) phenyl)- thien-3-yl)]perfluorocyclopentene (DTE-1) and [1-(2-methyl-5-(3- thienyl)-thien-3-yl)-2-(2-methyl-5(4-(1,3- dioxolane)phenyl)-thien-3-yl)]perfluorocyclopentene (DTE-2), were synthesized and their photochemical properties, such as photochromism and fluorescence were investigated. DTE-1 and DTE-2 have shown good photochromic behavior. Upon irradiation with 254 nm UV light, their color changed from colorless to blue, in which absorption maxima were observed at 590 nm and 592 nm in CH₂Cl₂. DTE-1 and DTE-2 also showed relatively strong fluorescence in different solvents when excited at 295 nm. While, their fluorescence spectra showed remarkable concentration dependence. In addition, near-field recording using DTE-1 as recording medium was performed successfully.

A photochromic diarylethene 1,2-bis(2-methyl-5-(2,2'-dicyanovinyl)- thien-3-yl)perfluorocyclopentene (1a) was synthesized. Its photochromic properties in different solution and PMMA film were investigated. While, fluorescence properties in different solution has also been discussed. The results of the research demonstrate that it has shown good photochromic behavior and relatively strong fluorescence in different solution at room temperature. At last, the dynamics of photochromic ring-opening and ring-closure reaction in different solvent was also elucidated. The result indicated that its cyclization/cycloreversion process was determined to be zeroth/first order reaction in different solution, respectively.

Epitaxial layers and monolayer of Ga_0.98 In_0.02As_0.24Sb_0.76 quaternary alloys lattice matched to GaSb substrates were grown by our home-made low pressure metal organic chemical vapor deposition (LP-MOCVD). Lattice mis-match (Δa/a~2.5%) between Ga_0.98In_0.02As_0.24Sb_0.76 quaternary alloys and GaSb substrate was obtained. Mirrorlike surface morphologies were investigated by SEM and AFM. Undoped Ga_0.98In_0.02As_0.24Sb_0.76 epitaxial layers grown on semi-insulated GaAs substrates indicates n-type with carrier density of 1.8×10¹⁷cm^-3 and electron mobility of 2551 cm²v^-1 s^-1. Growth at this temperature yielded a root-mean-square (rms) surface roughness of 160 nm. The effects of growth parameters on epitaxial layers were discussed. It is shown that under proper growth conditions, containing growth temperature (570~620°C), V/III ratios (2~6) and flux of carrier gas, smooth and high quality Ga_0.98In_0.02As_0.24Sb_0.76 epitaxial layers can be achieved.

Thermal annealing of amorphous SiC films deposited by pulsed laser ablation is performed at different temperature of 900-1050°C in vacuum condition. The structural and optical properties of the obtained films have been investigated by Micro-Raman scattering, UV- VIS transmission, and atomic force microscopy (AFM). It has been observed that the Raman bands related to SiC TO and LO modes appear and gradually shift to higher energy with increasing the annealing temperature, indicating that the crystallization of SiC occurs in the post-annealed films and their crystallinity increases. AFM results show that the post-annealed film is composed of compact nanoparticles and presents a rougher surface with respect to the as-deposited film. Optical band gaps deduced from UV-VIS transmission spectra are continuously increased from 1.90 eV for as deposited films to 2.45 eV of the annealed films at temperature of 1050°C. The formation of SiC nanocrystallines and the improvement of crystallinity can account for this blue-shift effect of the optical band gap.

In experiments, the energy band structures of one-dimensional photonic crystal (1-D PC) is researched. We get the relation between the band gap width and the number of the layers, the dielectric indices contrast, the center wavelength. The microcavity of 1-D PC is made. We study the reflection and transmission characteristics of the microcavity. Experimental results indicate the microcavity of 1-D PC can get a high reflection coefficient and a good stability and substantiality of the membrane layers in air.

Optoelectronic functional materials are divided into two categories as electronic functional material and photonic functional material. And the comparison of the two materials exhibits that the theory of electronic functional material, solid-state quantum mechanics, has developed quite ripe, but the theory of photonic functional material is still in the classical stage or quasi-classical stage. While today, photonic functional material has gradually developed into microscopic field, the deficiency of quantum mechanics in its theory has confined the development of photonic functional material. The optical theory in this paper is different from the traditional optical theory that originates from wave optics, but originates from ray optics and introduces quantum mechanics into ray optics, thus sets up the formula of ray optics quantum mechanics. The conclusion exhibits great symmetry between ray optics quantum mechanics and solid-state quantum mechanics. Nonrelativistic ray optics quantum mechanics is set up on the condition that light is confined near the axis. This paper introduces the construction of ray optics quantum mechanics concisely, and its main equations as well.

Because of its high photoemission performance, NEA photocathode has been developed rapidly and used widely in the recent several decades after it was found. In view of the problems existing in the research and producing of NEA photocathode, the study of property evaluation of NEA photocathode has been carried out in this paper. The spectral response decay of NEA photocathode has been measured, which provides valuable data for the stability research. The factors that influence the quantum yield of NEA photocathode are expounded. The characteristic parameters of NEA photocathode and the way of realizing property evaluation are introduced. The reflective GaAs samples are activated and evaluated by the activation and property evaluation system. The spectral response of NEA photocathode is measured on-line when it is being activated. The activation technique is analyzed and discussed combining with technology of XPS analysis. The property evaluation of NEA photocathode is realized. The properties of different NEA photocathode are compared. The problems in the research on NEA photocathode are pointed out.

By observing two-photon response and anisotropy of the light-induced voltage in Si-Al Schottky barrier potential of the Si MSM (Metal-Semiconductor-Metal) planar structure two-photon response optical detector. It is certified from the experimental and theoretical analysis that the built-in electric field generated by the Schottky barrier potential will induce the phenomena of optical rectification in Si photodiode. Thus, it is deduced that there must be double-frequency absorption (DFA) caused by phase-mismatch in the mechanism of two-photon response of Si photodiode. If the intensity of the built-in electric field is strong enough, the DFA will be the main feature of the two-photon response.

The Deformed-Split-Ring Resonators (DSRRs) require metal nanostructure on high transmission material substrate for optical application. In this article, a simple method of fabricating three- dimensional polymer nanostructure that use an UV-curable polymer as the resist is discussed. Because UV cure imprinting has high resolution which is about 100nm and high transparency, it is ideally suited for photonic and meta-material optical device applications. The fabrication combines several mass production technologies. The first one is photolithography, such as a stepper UV exposure system can make the nano scale pattern in photoresist, the second is to change the photoresist sample to become the nanoimprint mould by precise electroforming, the third is to use UV cure imprinting to transfer the DSRRs pattern on the UV-curable polymer. Finally, it is also the most important process is that to coat metals and metal lift-off that coating Ag to become buffer layer by sputter, then coating Au into the nanostructure and lift off Ag by HNO₃. The DSRR structure is implemented in high transmission UV-curable polymer with Au.

Diffractive optical elements in the form of surface-relief 'blaze' (echelette-type) structures diamond-turned onto the surface of conventional refractive lens elements are well-established and widely used. However, they suffer from limited broadband diffraction efficiency, which prevents the full benefits of hybrid optics from being realised. A family of diffractive optics, the blazed-binary optical element, is investigated to improve the broadband efficiency. Blazed-binary optical elements are diffractive components, composed of subwavelength (ie. with size smaller than the wavelength) ridges, pillars or other simple geometries carefully etched in a dielectric film, that mimic standard blazed-echelette diffractive elements. Their operation exploits effective-medium theory. We show that by exploiting the high dispersion of artificial material, diffractive optical elements which are blazed over a broad spectral range can be synthesized. A blazed-binary grating is designed to validate the broadband behaviour and practical aspects are investigated through the manufacture of sub-wavelength structures in a Gallium Arsenide substrate.

Hg₃In₂Te₆ material belongs to defect semiconductor group with concentration of stoichiometric vacancies up to 10²¹cm^-3, determining its unusual physical properties. In this paper we present the results proving the possibility to use this material for several types of high-efficient photonic structures, including self-calibrating photodiodes, high-speed photodiodes, multielement photodiodes with improved sensitivity and optical filters for spectral ranges 2-28μm. Performed photoconductivity measurements confirmed high photosensitivity of the material in wide spectral ranges of λ=0.35-1.85 μm, covering spectral sensitivity areas of CdS, CdSe, GaAs, Si and Ge. In comparison with these semiconductors, Hg₃In₂Te₆ has the lowest melting point (983K) making it possible to decrease energy consumption necessary for its synthesis. The experimental results also prove high quantum efficiency of the photoconductivity of Hg₃In₂Te₆ for hν = 0.74 - 3.5 eV. Mercury indium telluride is an ideal material for surface-barrier structures and hetero-junctions, due to low density of surface states and insensitivity to absorption of atmospheric oxygen.

The paper presents investigation results on surface modification influence of monocrystalline zinc sulfide substrates on their optical transmission and photoluminescence spectra. One of characteristic peculiarities of the samples considered is the presence of wide 2.5- 3.2 eV structureless irradiation band at CdS fundamental absorption region. Apart from this, absolute transmission decreases and transmission edge shifts into low-energy region of ~0.1 eV upon surface modification. Observed peculiarities of CdS optical properties can be explained by quantum-scale effects in nanocrystalline modified surface layer, experimentally detectable with atomic force microscopy.

Siloxanes, which can be viewed as hybrids of glass and organic materials, have been used to fabricate polymer waveguides and devices that exploit the large thermo-optical effect of this material. Siloxanes have many unique properties including good thermal stability, chemical resistance, tunable refractive index, tunable mechanical properties and excellent photo-stability. The refractive index of siloxane polymer is composition dependent and generally ranges from 1.4 to 1.54. Introduction of porosity or composition modification can further expand refractive index range to 1.15~1.63. The loss and absorption characteristics for a variety of silicone-based polymers are examined and an example of a UV curable polymer coating illustrates the flexibility of the silicone polymer family to be tailored to meet specific application needs.

In this paper, the absorption and fluorescent spectra of Nd³⁺: KGd(WO₄)₂ at room temperature were measured. According to Judd-Ofelt theory, the intensity parameters Ω_λ(λ=2,4,6) were worked out. With these values, the oscillator strength, spontaneous radiative rate, branching ratio, integrated emission cross-section and laser wavelength 1.06μm emission cross-section were calculated. The energy-level of Nd³⁺ in KGW was given, the possibility to produce 1.33μm laser and the relationship between output and pumping power in different Nd³⁺ion-doped KGW were discussed.

A design is described for photoelectric equipment reconnaissance using an active laser detection system based on the 'cat's eyes' effect of optical windows and the technique of non-linear Optical Phase Conjugation (OPC). With 'cat's eyes' effect, the detection of uncooperative target can be translated into one of a cooperative target, so the ratio of returned laser for remote target can be increased. The receiver used for receiving retro-reflection laser employs a laser amplifier, a Phase Conjugating Mirrors (PCM) based on Stimulated Brillouin scattering (SBS), as it allows for compensation of spatial non-uniformity on the laser pass coming from atmospheric turbulence. The system is thus composed of a laser emitter, a laser receiver and an information processing subsystem. The light reflected by the optical window of target acts as the beacon light. The phase conjugate light which is produced by the laser receiver according to the wavefront aberration of the beacon light is emitted to the target, and reflected by the target to the receiver and information processing subsystem separately. This system is capable of sustaining oscillation between target and laser receiver, locks onto a target and then detects its position and velocity accurately.

The electronic structures, dielectric function, complex refractive indices and absorption spectra of the perfect PbWO₄ crystal and the crystal containing oxygen vacancy V_O²⁺ have been calculated using full-potential (linearized) augmented plane-wave (LAPW) + local orbitals (lo) method with the lattice structure optimized. The results indicate that the perfect PWO crystal does not occur absorption band in the visible and near-ultraviolet region. However, the calculated absorption spectrum of the PWO crystal containing V_O²⁺ has two bands peaking at 370nm and 420nm in the visible and near-ultraviolet region respectively. It reveals that the 350nm and 420nm absorption bands are related to the existence of V_O²⁺ in the PWO crystal.

An improved method for the preparation of [2,2]-paracyclophane, which is the monomer of poly-p-xylene widely used as high quality electrical coating material, by Hoffmann elimination employing p-methyl-benzyl chloride and trimethyl amine as main raw materials was developed. Influence of solvent, reaction time, reaction temperature etal on the yield of paracyclophane was investigated experimentally. Suitable reaction parameters were obtained as follows: n(Alkali) : n(Quaternary ammonium) is 5:1; catalyst: 0.2% cupric salt; with 1,4-dioxane as solvent and 0.2% sodium borohydride as reducer, and N₂ as protection gas; reaction temperature 110°C, reaction time is 30 hr, at the condition, the yield of [2,2]-paracyclophane is 78.6%, its purity is over 99.5%, with melting point 284-285°C. Analysis results by IR and melting temperature measurement etal identify the substance synthesized is [2,2]-paracyclophane. And the materials used is industrially available and better yield was obtained comparing with the values present in the patent literatures.

The third-order nonlinear optical susceptibility χ⁽³⁾, nonlinear refractive index n2 and time response for for aromatic organism (naphthalene C₁₀H₈, anthracene C₁₄H₁₀, dibenzathracene C₂₂H₁₄ and dibenzopentracene C₃₀H₁₈) were measured with forward DFWM. The absorption spectra, excitation spectra and fluorescence spectra for them were given. The induced mechanism of the nonlinear effects, affecting factors and relation with the molecular structure were discussed.

The InAs_0.04Sb_0.96 epilayers with a cutoff wavelength of 12 μm were successfully grown on semi-insulating (100) GaAs substrates using melt epitaxy (ME). Fourier transform infrared (FTIR) transmission spectra reveal a strongly band gap narrowing for this alloy. A room-temperature band gap of 0.1055 eV is demonstrated via analyzing the temperature dependence of the carrier density for the InAs_0.04Sb_0.96 layers, which is in good agreement with the value obtained by transmittance measurements. The temperature dependence of energy band gap for InAs_0.04Sb_0.96/GaAs is studied between 12 K and 300 K by measuring the absorption spectra. An electron mobility of 44,700 cm²/Vs with a carrier density of 8.77 × 10¹⁵ cm^-3 at 300 K, an electron mobility of 21,500 cm²/Vs with a carrier density of 1.57 × 1015 cm^-3 at 77 K, and a peak electron mobility of 48,000 cm²/Vs at 245 K have been achieved for a 100 μm thick epilayer. These results indicate its potential applications for infrared photodetectors and high-speed electron devices.

High energy lasers processing of materials is knowing an increasing interest since it not only can make manufacturing faster, cleaner, and more accurate but also because it opens up entirely new technologies and manufacturing methods, that are simply not available by using standard techniques. In this paper, an experimental set-up, based on pulsed KrF excimer Laser, assembled for surface patterning of mono and two-dimensional, (1D-2D), micro and submicro structures on LiNbO₃(LN) crystal, will be described in detail. The apparatus has been used to produce photonic structures in LN, both by patterning of PMMA photoresist, and by direct surface patterning through laser ablation or direct laser writing. The structures and properties of the photonic crystals fabricated by using this apparatus have been investigated, and the preliminary results will be presented.

The nonlinear refraction index n₂ and the reverse saturation absorption (RSA) coefficient β of a series of hydroxylphenyl porphyrin have been measured using single beam Z-scan technique with a 8 ns laser pulse at 532nm and the third-order nonlinear susceptibility χ⁽³⁾ of the samples are calculated. It is seen that a series of hydroxylphenyl porphyrin have large value of the reverse saturation absorption and cubic nonlinear refraction. The effects of molecular structures on the third-order nonlinear optical properties were discussed. Experimental results show that the effects of different numbers and different positions of substituent to the nonlinear refraction of porphyrin are evident.

Since the gradient index material has important applications at photoelectric system, imaging system, and integrated-optical system. Now, researches on gradient index material containing silver ions are more popular, it is difficult to get glass with high silver content as silver ion is extruded from molten glass at the molten temperature. Two-step ion-exchange process including Ag ⁺- Na⁺ and Na⁺ - Ag ⁺ ion-exchange is used to get gradient index. This paper is based on the research in our lab, by adjusting the glass composition to get a series of sodium-rich glass then drawing the fusioned glass into fiber with diameter of 1mm used for ion-exchange. We used mixed molten salt for ion- exchange, then we researched on the choice of silver salt, the advantage and disadvantage of mixed molten salt and single molten salt, and the coloring up problem after ion-exchange.

In this paper electron trapping optical storage materials CaS: Eu, Sm was prepared by high temperature solid state method. XRD analysis indicates that the sample obtained is with face-centered cube structure. with a lattice parameter of 5.694A. Optical properties of CaS: Eu, Sm were studied. Excitation spectrum shows that the material can be excited by ultraviolet and visible light. The excitation peaks are at 250-300nm and 450-550nm respectively ranging from 250-550nm. Emission spectrum is composed of three peaks at 567nm, 603nm and 650nm respectively. Photo-stimulation excitation spectrum is a broadband spectrum between 800nm and 1600nm peaking at about 1200nm. Photo-stimulated luminescence peak is at 635nm.

Biphenyl forms at normal pressure and temperatures below 40 K incommensurate crystalline structures with physical properties varying in space on a scale of nanometers. As biphenyl crystals are optically transparent, there is a possibility to study these natural nanostructures optically, by doping the host crystal with nanoscopic probes with optical properties depending on their local environment. It has already been demonstrated that terrylene impurity molecules in polycrystalline biphenyl sample can successfully play the role of such kind of sensitive nanoprobes when studied by the methods of high-resolution laser spectroscopy. We report growing of thin biphenyl monocrystals doped with terrylene molecules at very low concentrations. These sublimation-grown flakes can be studied at liquid helium temperatures using the technique of single-molecule spectroscopy. Compared to polycrystalline biphenyl samples, much higher signals and better signal-to-noise ratio can be achieved in single-molecule spectra. This allows to perform much faster spectral scans to find intensive single-molecule lines even in very dilute samples in spite of a very broad inhomogeneous absorption band of terrylene in biphenyl. Fast scanning also allows observation of single-molecule lines with much better temporal resolution, revealing processes of spectral diffusion occurring at different time scales. This can be helpful in our attempts to learn about the role of the matrix incommensurability in spectral features observed. Extremely high variability of temporal and spectral behaviour of terrylene single-molecule lines is reported, which is unusual for crystalline hosts.

A model of photonic crystal fiber (PCF) with tapered high-index core by GeO₂ doped in silica glasses is supposed. Based on finite different approximation of the semi-vector helm-holtz equation, the character of dispersion and modal field areas about this kind of PCF are investigated. Results demonstrate that dispersion parameter can change gradually in positive dispersion region or negative dispersion region, even can change from positive to negative dispersion region when the air hole and pitch are fixed, only the core radius of the PCF is tapered. The kind of PCF is designed for special dispersion-related applications. Especially, it can offer dispersion self-compensation in some optical devices.

The paper reports a new up-conversion luminescence material based on Yb ³⁺, Er³⁺ co-doped germanate glass ceramic, the matrix system is GeO₂-PbF₂-Nb₂O₅. The luminescence characteristics of the Yb3+ , Er3+ co-doped glass ceramic have been studied. The structural properties of the germinate glass ceramic have been analysed by X-ray diffraction. Under the condition of 980nm semiconductor laser pumping, the green fluorescence intensity shows that the existence of niobate components plays an important role for up-conversion luminescence.

The red long afterglow phosphor CaTiO₃ activated with Pr³⁺ was formed by wet-dry method in this study. The luminescent properties of this sample had been studied systematically. The X-ray diffraction (XRD) patterns of the powder reveal that CaTiO₃:Pr phase was obtained by wet-dry process. The afterglow decay curves were measured and the afterglow time was over 40 minutes. The excitation spectra and emission spectra were measured. The emission peak was at 613nm, due to the transition of ¹D₂-³H₄. With the function of weak crystal field the main emission divided into 612nm and 614nm. In spite of the main emission peak, phosphor had a shoulder emission peak at 620-628nm. Changes of Pr³⁺ molar ratio had little effect on the emission spectra, but with Pr³⁺ 0.2%, phosphor had an emission peak at 626nm. The excitation peak was at 342nm, with a shoulder peak at 400nm. Compared with SS, this less time and less energy was used and the same result is obtained.

The present paper provides a novel process for preparing chlorocyclophosphazene characterized by the combination of: (I) The first step of reacting phosphorus pentachloride sublimated with ammonium chloride in an inert organic solvent (such as chlorobenzene) in the presence of N₂ and Zncl₂, and distilling off the solvent from the resulting reaction mixture to obtain a reaction product consisting essentially of chlorocyclophosphazene (up to 93%), and (II) the second step of contacting a solution of the reaction product in the heptane with water in proption at temperature of about 60°C, separating the resulting aqueous layer from the organic layer, and isolating from the organic layer a mixture of chlorocyclophosphazene consisting essentially of the hexachlorocyclotriphosphazene which yield can reach up to 80%. Factors affecting on the process were also discussed in detail. The results show that the technology is time saving(only 2.5 hours) under the suitable condition and the total fractional conversion is achieved 99%.The hexachlorocyclotriphosphazene were characterized by IR spectra, and the purity of product is over 98%.

Eu(III)-trimesic acid (TMA) luminescent complex Nanorods were synthesized in the polyvinylpyrrolidone matrix. The obtained sample was characterized by elemental analysis, Inductively Coupled Plasma-atomic emission spectroscopy(ICP-AES), X-ray diffraction(XRD), Fourier-transform Infrared spectroscopy(FT-IR), transmission electron microscopy(TEM) and photoluminescence spectra (PL). The results demonstrated that its chemical constitution is PVP/Eu(MTA) • 2H₂O. The XRD patterns show that the complex was a new kind of crystal whose structure is totally different with the ligand. TEM image indicated that the complex is nanocrystal with rod shape in one dimension, the size of rod diameter is about 50~100 nm, and the length ranges from hundred nanometer to a few micrometers, in addition, the dispersity is better. Photoluminescence analysis indicated that the complex emits Eu ³⁺ characteristic luminescence under ultraviolet excitation. TG-DTA curves indicated that the complex is heat stable under the temperature of 454°C. Therefore an thermal decomposition mechanism is: Eu(MTA) • 2H₂O->Eu(MTA)-> Eu₂O₃.

High-quality zinc selenide (ZnSe) single crystals were grown by the high-pressure Bridgman method (HPB). Physical vapor transportation (PVT) method was adopted to purify ZnSe (4N) polycrystalline materials. The purity of starting material can be improved to 5N after the purifying process. The effect factors of purifying temperature, oxygen percentage and pressure etc. to the crystal growth were studied. The homogeneity analysis shows that the ZnSe single crystals obtained are highly homogenous and integral. Optical properties analysis shows that the transmittance coefficient of ZnSe single crystal is above 70%, with high refractive index and low absorption coefficient.

In this paper, the Equivalent Step-Index-Fiber Method (ESFM) for multicladding fibers is applied to microstructured polymer optical fibers (MPOFs). Based on an average model, this method is used to analyze one type of MPOFs with ring structures and the results obtained are compared to that of the multipole method. Meanwhile, these results indicate that the type of MPOF can enable single-mode to operate with large mode areas at optical wavelengths and that the size and the arrangement of the holes and the dimension of the effective core radius have effect on the characteristic of the MPOF. The MPOF with ring structure can be acted like a multicladdding fiber if the hole or the air-filling fractions in these ring structures is small enough.

The red phosphors of Y₂O₂S:Eu³⁺ were synthesized by combustion reactions from mixed metal nitrate reactants and a fuel CH₄N₂S with ignition temperatures of 450°C. Sulfur was produced by CH₄N₂S decomposed at high temperature. Y₂O³ decomposed by Y(NO₃) ₃ reacted in Sulfur atmosphere to synthesize Y₂O₂S host. From altering the ratio of CH₄N₂S and metal nitrate, the pure phase Y₂O₂S:Eu³⁺ red phosphor was obtained. The conclusion was proved by XRD patterns and emission spectrum.

This document shows the desired format and appearance of a manuscript prepared for the Proceedings of the ICO20. It contains general formatting instructions and hints about how to use it. The (Y_0.99Nd_0.01)₃Al₅ O₁₂ nano-sized powders were synthesized by low temperature combustion (LCS), using Nd₂O₃, Y₂O₃, Al(NO₃) ₃♦9H₂O, ammonia water and citric acid as starting materials. This method effectively solves the problems caused by solid-state reaction at high temperature and hard agglomerates brought by chemical precipitation method. The powders were characterized by TG-DTA, XRD, TEM respectively. The study focused on the photoluminescence (PL) spectra of (Y_0.99Nd_0.01)₃Al₅ O₁₂ ceramic green and sintered disks. The experiments show that the forming temperature of YAG crystal phase is 850°C and YAP crystal phase appearing during the calcinations transforms to pure YAG at 1050°C. The particle size of the powders synthesized by the LCS is in range 20-50nm depending on the thermal treatment. The effectively induced cross section (σ_in) with the value 4.03×10^-19cm² of (Y_0.99Nd_0.01)₃Al₅ O₁₂ ceramics is about 44% higher than that of single crystal.

In this paper, rare earth (Eu³⁺, Sm³⁺) binary chelates with hexafluoroacetylacetone(HFA), thenoyltri fluoroacetylacetone (HTTA), and dibenzoylmethide(DBM) were synthesized, respectively. Then the fluorescence properties of the chelates Eu(TTA)₃, Eu(HFA)₃, Eu(DBM)₃, Sm(TTA)₃, Sm(HFA)₃ and Sm(DBM)₃ in benzene were investigated. It was found that the fluorescence peak at 614nm related to the transition of ⁵D0->⁷F2 of Eu³⁺ was the strongest in Eu(TTA)₃. Based on this, the concentration (between 0.05-0.5wt.%) influence of Eu(TTA)₃ on fluorescence intensity in Eu(TTA)₃-doped PMMA was studied. The results showed the fluorescence intensity increases with Eu(TTA)₃ concentrations except that no fluorescence peak was detected for 0.05wt.% Eu(TTA)₃-doped sample. However, the sharp fluorescence peak accidentally occurs at 614nm when 0.04wt% Eu(TTA)₃ and 0.04wt% Sm(TTA)₃ were co-doped in PMMA. Further investigation revealed that similar fluorescence enhancement occurred for all samples co-doped with Eu(TTA)₃ and Sm(TTA)₃. It indicated that Sm(TTA)₃ has a strong sensitization effect on the fluorescence of Eu(TTA)₃. Besides, it was also found the sensitization effect could be decreased with the increasing Sm(TTA)₃ concentrations for a fixed Eu(TTA)₃-doped content. Finally, two possible energy transfer mechanisms were analysed.

In this article, we have investigated energy upconversion process in erbium doped oxyfuoride tellurite glasses exciated with 980 nm diode laser. The glasses used in measurements are with a mol% composition of 70TeO2-9PbF2-190AlF3-10BaF2-1Er2O3. The Ω_s intensity parameters, the radiative rates, the branching ratios and the fluorescence lifetimes were calculated based upon the Judd-Ofelt theory and the experimental absorption spectrum. Under 980 nm excitation, efficient 530, 544, and 665 nm upconversion emission are due to two-photon absorption processes.

From the optical absorption measurements, the Judd-Ofelt parameters were computed using Judd-Ofelt theory. According to the radiative lifetime obtained from the Judd-Ofelt parameters and the measured lifetime, the1.5μm quantum efficiency was calculated. The quenching effect of OH upon the lifetime of 1.5μm emission was investigated. From the absorption sideband measurement of glass host, the value of optical band gap was estimated. The McCumber theory was used to calculate the stimulated emission cross-section and in approximate agreement with experimental one if the emission spectrum could be obtained accurately. The gain coefficient spectra were computed.

We report the excitation of the non-steady-state photoelectromotive force (photo-EMF) in the layered boron nitride crystal. Boron nitride crystals are characterized by an unique combination of physicochemical properties that advance its wide application in various areas of science and technology such as vacuum technology, production of the microelectronic devices, x-ray lithography. The main goal of our work is to present possibility to expand the non-steady-state photo-EMF technique for the new class of diamond related materials with extremely wide band gap (Eg = 5.67 eV for BN). The investigated pyrolytic BN crystal was grown using the chemical vapor deposition method. It consists of the monocrystal layers of the rhombohedral modification with thickness of 2000 A separated by thin (~100 A) layers of the hexagonal modification. The photo- EMF signal is generated by two coherent laser beams (λ = 532 nm) one of which is phase modulated. Both the diffusion regime of signal excitation and the excitation in an external sinusoidal electric field are investigated. The measurements performed using standard diffusion regime of photo-EMF generation reveals rather low hole photoconductivity σ₀ = (0.9-2.4)x10^{- 10}Ω^-1 cm^-1 at light intensities I₀ = 0.22-0.86 W/cm² and small diffusion length L_D = 35 nm of photoholes. We also measure the μτ- product and diffusion length using novel technique of signal generation in an external ac field: μτ= 1.0 x 10^-9 cm²/V, L_D = 50 nm. The influence of the layered structure of the investigated BN crystal on the effect of the non- steady-state photo-EMF is discussed.

We show by both experiment and theory that single layered metallic photonic crystals containing spiral-like patterns possess multiple resonance frequencies in linear scale, leading to multiple stop bands and pass bands for electromagnetic waves over a wide frequency regime. These resonances originate from the fine structure of single unit with spiral-like patterns, and are independent to the angle and polarization of incident waves. In additional, such a metallic plate with only one single spiral-like pattern can effectively reflect a near-filed source near the resonance frequencies. This kind of metallic photonic crystals can be applied in multi-band electromagnetic wave devices with sub-wavelength size.

The immobilization of antibodies on solid surface has been widely studied in elucidating immunoassay and in developing immunosensor. In this paper, FITC-labeled goat anti-human IgG were covalently immobilized on 3-aminopropyltriethoxysilane (APTES) and glutaraldehyde (Glu) to modify the distal end of a fiber-optic probe. The higher density and stability of FITC-labeled goat anti-human IgG could be obtained on the fiber surface modified with APTES-Glu than that on the non-modified fiber surface by evanescent excited fluorescence spectroscopy. Furthermore, red shift of the FITC fluorescence dye emission peak was observed on different fiber surface, exhibiting different interaction between FITC- labeled antibody and surface. Finally, under these conditions antigen-antibody reaction was investigated as an immunosensor. Detection limit of the evanescent wave optic-fiber biosensor is 10ng/ml.