This PDF file contains the front matter associated with SPIE Proceedings Volume 6831, including the Title Page, Copyright information, Table of Contents, and the Conference Committee listing.

We propose and realize a micro-cylinder mode in photonic quasicrystal (PQC) on the top of an edge-emitting GaN light emitting diodes (LEDs) with 30 μm indium tin oxides (ITO) covered and 8 μm GaN exposed broad-stripe. A well-defined hexagon-like localized state following a C_6v symmetry is identified from the PQC micro-cylinder arrays. Enhancement factor of the surface light extraction from 12-fold PQC patterns on electrical current injected GaN-based light emitters is 2.4 times higher than non-patterned regions, which is observed by scanning near-field optical microscopy (SNOM). According to the near-field optical images, micro-cylinders can be considered as nano-optics sources because the electromagnetic energy is strongly concentrated due to the wave guide modes and the beaming effect of the surface microstructures.

We report that the transmitted evanescent light beam under total reflection will experience a lateral displacement similarly to that of the reflected beam, called Goos-Haenchen (GH) effect. By a dielectric thin film coated onto the dielectric surface, which is usually considered as the near-field enhanced configuration in atom optics, we indicate that the displacement of the transmitted evanescent beam can be greatly enhanced to several tens of wavelengths at transmission resonance under total internal reflection. Numerical simulations have been performed and it is shown that the transmitted evanescent beam maintains well the shape of the incident beam when the thickness of the thin film is required to be of the order of wavelength. Further, it is demonstrated that the stationary-phase approach is also applicable to transmitted evanescent beam and the GH displacement of the transmitted beam is just half the GH displacement of the reflected beam. The discussions presented here may arouse interest in atom optics and near-field microscope.

We analyze the resonant properties in surface plasmon polaritons nanocavities and study the resonant transmission spectrum of light through a sub-wavelength metallic nanocavity composed by two pieces of finite silver thin slabs with nanometer configurations of periodic sinusoid profile on their inner boundary, setting by face-to-face arrangement with a separated spacing. The boundary elements method (BEM) is adopted for analyzing the optical behavior of these metallic nanocavities. We investigate the influence of the number of the grating period on the optical resonant behaviors of the nanocavities. The numerical results indicate that the wavelengths of resonant peaks are well agreed with the predicted resonant wavelength. Furthermore, the number of the resonant wavelength from the scattered resonant transmission spectrum increases as the number of the grating period is increased, and the resonant peaks shift to the longer wavelength while the number of the grating period is increased. It is believed that our analysis will provide important information for designing novel cavity that can select the wavelength or realize ultra-minitune optical sources that can be easily integrated in the all-optical communication system.

Two formulas for microscopic interaction force have been suggested in this paper. Some interesting results such as the invariant light speed in free space and the πphase change or one half of wavelength delay could be interpreted using the dynamic equations based on our suggestions although the former is the foundation of relative theory, the latter is all-known phenomenon in optics. There is no concise or clear understanding to them at least at present so this gap might be filled by our work. At the same time several well-known classical or modern optical experiments are also proved or logically analyzed. This fact shown that our suggestions are not only considerable assumptions but also revealed the interaction relation between microscopic particles. Its' worth to note that we have tested the microscopic geometric scale (GAS) pointed a short time before by us as well as the microscopic interaction force using Fizeau experiment. Besides this some other interesting results, such as the possible geometrical action scale of gravitational field particle, the new method to measure the constant of gravitation and time evolution equation for media index etc.

A micro-aperture vertical-cavity surface-emitting laser (VCSEL) is a kind of active nanophotonics devices. It can confine the optical near-field to a nanometric light spot of high intensity. The confinement effect is usually implemented by a round aperture. A bow-tie aperture can do it better if the incident light polarizes along the line between its ridges. However, a conventional VCSEL does not have a definite polarization state, so a bow-tie aperture VCSEL is very difficult to be implemented. In order to solver this problem, a rectangular aperture array is employed to improve the polarization state. Two bow-tie aperture VCSELs with and without their polarization state improved are fabricated. Their near-field intensity distribution is measured and compared. The measurement results demonstrate that the near-field intensity is enhanced dramatically when the polarization state is improved. So the confinement and enhancement effect of a bow-tie aperture can be obtained on the basis of a micro-aperture VCSEL.

A new white-light interferometric technique using in measurement of thickness based on the theory of spectral-domain interference is specified in the paper. The theory of spectral-domain interference broke the limitation of coherence length in interferometry, and gain a much longer measuring range than in time-domain. The optical fiber was applied to Michelson interferometer with the advantage of much convenience of system design. Spectrometer is used to get the spectral-domain signal. With a simple arithmetic, the optical path difference which is related to some parameter could be acquired. A thickness measuring system is designed. The measuring range could be calculated, the error could be forecasted. The simulated result indicats the error of white-light spectral interferometry can be controlled within several nanometers.

The theoretical method to design negative refractive index metamaterials by single negative permittivity metamaterials is presented. By designing the electric and magnetic response metamaterials separately, the complexity of the design work can be simplified a lot. For the magnetic response metamaterials, the metallic post structure is adopted. Varying the height of the post, the response wavelength can be adjusted linearly. For electric metamaterials, wire-mesh structure is adopted. The effective material parameters, including refractive index, impedance, permittivity and permeability are given. Such a structure has negative refractive index during a broad frequency band and easy to design.

An ultracompact gas-sensor based on the two-dimensional photonic crystal microcavity is presented. The sensor is formed by a point-defect resonant cavity. The transmission spectrums of the sensor with different ambient refractive indices ranging from 1.0 n = to 1.01 n = are calculated. The calculation results show that a change in ambient refractive index of Δn=1×10^-4is apparent, the sensitivity of the sensor (Δλ/Δn) is achieved with 433nm/RIU(when lattice constant 520 a=520nm), where RIU means refractive index unit . The properties of the sensor are analyzed and calculated using the plane-wave expansion (PWE) method and simulated using the finite-difference time-domain (FDTD) method. Using the fabry-Perot cavity mode, the performances of the refractive index sensor are analyzed theoretically. The sensor is optimized using the photonic crystal waveguide structure and simulated using the FDTD method. As the small sensing area (~10μm²) of the device would require only ~1fL sample analyte, these ultracompact gas sensors would be widely used in little sample analyte in gas measurement.

In this paper, by using the transfer matrix theory and the dispersion relation principle, via math tool processing numerical value simulation get the energy band, the limited field and the dispersion characteristic of one-dimensional photonic crystals with negative-index materials, we find there are two photonic band gap, the lower forbidden band which is called zero-n gap remains nearly invariant under a various incident angle, while the higher one which is called Bragg gap changes ceaselessly with the increasing incident angle. Through introducing the defect we found that the defect mode inside the zero-n gap remains invariant with the scaling of non-defect part. Conversely, the defect mode inside the Bragg gap shifts greatly in frequency with scaling. The studying of the dispersion relation shows that the width of the zero-n gap enlarges, but the middle of each gap hardly changes, on the contrary the middle of a Bragg gap will shift noticeably while the width of the gap will change a little when the ratio of the thicknesses of the two types of layers varies and that the zero-n gap that distinguishes itself from a Bragg gap in that it is invariant with scaling. The emphasis of this paper lies in analyzing the characteristic of this type of photonic crystals. zero-n gap enlarges, but the middle of each gap hardly changes, on the contrary the middle of a Bragg gap will shift noticeably while the width of the gap will change a little when the ratio of the thicknesses of the two types of layers varies and that the zero-n gap that distinguishes itself from a Bragg gap in that it is invariant with scaling. The emphasis of this paper lies in analyzing the characteristic of this type of photonic crystals.

The performance of a optical component is greatly dependent on its surfaces. There are many ways to measure and evaluate a surface so far, but actually no one knows exactly what a "real" surface likes, and thus makes some measurement unexplainable. This paper develops a way to construct various synthetic surfaces. Referred to actual AFM measurement, regular or irregular surfaces can be created and studied. Bumps, scratches, granules, profile errors and other construction elements can be added to form a very complicated virtual surface. The number, size and distribution of these elements can be changed, and if necessary, the surface roughness can be controlled in a specialized range. As these surfaces are created synthetically, we know exactly what construction these surface contain. The height data of created virtual surfaces can be transferred into the file that AFM instrument can read and handle. As a typical example, a very complicated surface is created step by step in this paper, and its PSD for each step are calculated. This process mikes it very clear how the surface component element affect its PSD function, and is benefit to our better understanding of real surface construction.

Nanoindenter provides an approach for assessing mechanical properties in micro-electronics devices and films based on quantitative, controlled nanoindentation of surfaces, with the convenience of modern automation. It is also suitable to measure mechanical properties of biomaterials. Nanoindenter for biomaterial testing in bone and dentin was widely used. Recently some studies of nanoindentation properties in insect were carried out. While the surface roughness of natural biomaterials problem should not to be ignored in nanoindentation testing. The surface roughness will critically affect the precision of result of nanoindentation testing and caused error data. In this paper, the biomaterials specimen preparation methods for nanoindentation testing will be reviewed.

A off-axis deposition method, which aligns the edge of the substrate to the normal of the plasma plume and makes the edge of the plasma plume at the center of the substrate, is used to deposit large-area DLC films. The distance between the target and the substrate and the deposition time are optimized to obtain uniform and large area DLC films on the K9, fused silica glasses and ZnS with the diameter of 50 mm. It is shown that the thickness uniformity of the films with off-axis deposition method is much better than that with the on-axis method. The thickness uniformity for off-axis and on-axis deposition is compared, and the possibility for preparing large-area uniform films is discussed. In addition, the transmission of ZnS with DLC coated is improved.

Our recent work revealed that, when nanofluids containing a modest volume fraction of nanoparticles are illuminated by a parallel monochromatic laser beam, speckles would be formed. Therefore, it is realized that Laser Speckle Velocimetry can be used to measure the velocities of nanoparticles in nanofluids.¹ This paper aims to investigate the laser transmission properties of nanofluids via experiments and numerical simulations, so as to determine the proper conditions for the formation of speckles. First, experiments are performed to measure the light transmittance of nanofluids at different laser power and different particle volume fraction. Then, Monte Carlo simulations are carried out based on a physical model considering random collisions between photons and nanoparticles to simulate light propagation in nanofluids. The numerical results are in good agreement with the experimental results, and a final conclusion is drawn that the particle volume fraction and particle size are the prime factors that influence the light transmittance.

We have considered a two dimensional narrow semiconductor ring with sectorial barriers that is threaded by magnetic flux. Using numerical diagonalization techniques, we have presented the diagrams of the energy spectra versus the magnetic flux. For a constant value of the barrier height, with enhancement of the number of barriers, the energy levels shift to higher energies and the degeneracy of the system increases. We have also investigated the behavior of the energy levels with the magnetic flux for different values of the barrier height. The fluctuation of the energy levels decreases, as the barriers' height increases.

We propose a novel optical fiber-to-waveguide coupler for integrated optical circuits. The proper materials and structural parameters of the coupler, which is based on a slot waveguide, are carefully analyzed using a full-vectorial three dimensional mode solver. Because the effective refractive index of the mode in a silicon-on-insulator-based slot waveguide can be extremely close to that of the fiber, a highly efficient fiber-to-waveguide coupling application can be realized. For a TE-like mode, the calculated minimum mismatch loss is about 1.8dB at 1550nm, and the mode conversion loss can be less than 0.5dB. The discussion of the present state-of-the-art is also involved. The proposed coupler can be used in chip-to-chip communication.

A nonradiating, spatially confined optical field based on surface plasmon polaritons (SPPs) on a corrugated surface of metal film is proposed. With the help of the surface plasmon band-gap nano-structure, SPP can be collected in a spatial region beyond the diffraction limit and form a confined optical field, which can be used as a nano-source in near-field. Compared with other types of near-field sources, such confined optical field provides higher intensity, and the spot size of the nano-source can keep constant within certain distance. By using the method of Finite-Difference Time-Domain (FDTD) is used to simulate the distributions of the confined optical field, two types of confined optical fields based on SPPs excited by prism and by grating, respectively, are demonstrated in 2D- and 3D-space. Such confined optical field as a nano-source, is promising to be applied to near-field imaging and optical manipulation, and has potential applications in nano-photonics devices based on SPP.

Concerns on quantum dots (QDs) have been continuously increasing because of their advantages on photophysical properties. Water soluble CdTe/CdS core-shell and CdTe/CdS/ZnS multi-layer QDs were synthysized with mercaptopropanoic acid (MPA) as stabilizer in aqueous phase in the current research. The obtained QDs were characterized with fluorescence spectrum (FS), and quantum yields (QYs) was calculated base on the resulting data from FS. Comparing with CdTe core, red-shift of maximum emission wavelength (MEW) of CdTe/CdS was observed, which indicated the growth of QDs size. To obtain high QYs of CdTe/CdS core-shell QDs, several methods and different reaction conditions were investigated and discussed, such as dependence of Cd²⁺ concentration, dependence of pH, influence of S^2-:Te^2-, and effect of Cd²⁺:S^2- etc. Among all of discussed methods, QYs of core-shell CdTe/CdS is generally degressive with refluxing time elapsing. The best QYs of 79.8% can be achieved when pH was set at 8.5, Cd²⁺:S^2-=1:0.1 (mol ratio). Moreover, CdTe/CdS/ZnS multi-layer QDs was prepared, and results via FS indicated a further red-shift from 554 nm to 646 nm comparing with CdTe/CdS QDs, but QYs decreased to 14.0%. QDs currently discussed in this research are easily synthesized, and safe to organism, i.e. biocompatible. They will be useful in applications of biolabeling, imaging, and biosensing based on fluorescence resonance energy transfer (FRET).

Core-shell gold nanoparticles film was fabricated by using nanolithography and self-assembly monolayer technology. The film exhibits unique optical properties and has strong surface enhanced Raman scattering activity. The relationship between nanostructure and surface electrical field was studied by employing pyridine as the SERS probe. It was found that particle size and interparticle space are of important factors. The enhanced ration is measured more than 10⁴.

Study of plasmon-induced charge transfer mechanism in gold-TiO₂ system is crucial and promising in the solar cell application. To investigate charge separation and recombination dynamics in gold/TiO₂ nanoparticle systems, we used ultrafast visible-pump/IR-probe femtosecond transient absorption spectroscopy method. In our experimental study, anatase TiO₂ with different particle size 9 nm and 20 nm were chosen as electron acceptors. Plasmon-induced electron transfer from the gold nanoparticle to the conduction band of TiO₂ was studied by optical excitation of the surface plasmon band of gold nanoparticle at 550 nm. The transient absorption kinetics were studied by probing at 3440 nm to observe intraband free electron adsorption in TiO₂. In our experimental results, electron injection was found to be completed within the apparatus time resolution (240 fs), the charge recombination decay within 1.5 ns was nonexponential. And when laser power changed from 0.5 μJ to 1.9 μJ, the recombination decay didn't depend on the excitation intensity. It is interesting that we found the measured back electron transfer kinetics up to 1.5 ns were strongly dependent on the particle size of TiO₂. The plasmon-induced charge transfer mechanisms will be discussed.

We use a tight-binding Hamiltonian for an infinite quantum wire with substitusional disorder of A and B atoms in a uniform electric field and calculate the density of states by coherent-potential approximation method. The electric field produces a little oscillation on the local density of states and by increasing the strength of the electric field the amplitudes of the oscillations grow up and they becomes more localized too. Also, by increasing the strength of the electric field, the range of the extension of the energy spread out. The density of states at E=0 versus a parameter which depends on electric field, is calculated and it shows oscillating pattern too. The local density of states for the different sites is calculated and all of them are similar except a shift which is proportional to the strength of the electric field.

In the present paper, the two-dimension photonic crystal (PC) polarization coupler is mainly studied. The PC waveguide coupler with a single row of dielectric rods in the interaction region is composed of square-arrayed dielectric pillars in air. The photonic band gap maps are calculated by using plane wave expansion (PWE) method and the effects of the geometrical parameters of the scatterers between two coupling channels on the property of the PC couplers are analyzed by using the finite-difference time-domain (FDTD) method. The simulation results show that the coupling property is sensitive to the shape variation of scatterers. The shape variation of scatterers between the two coupling channels will reduce coupling length greatly.

ITO thin films were prepared by oxygen ion-assisted electron beam (EB) evaporation technique onto K9 glass substrate at low temperature and effects of substrate temperature, oxygen flux on the structure, electrical and optical properties of ITO thin films were investigated. An advanced plasma source (APS) was used to produce high density argon and oxygen ion flux to cause electron degeneracy in the band gap by introducing non-stoichiometry in the ITO films to improve the conductivity of the prepared films. The structure of the ITO thin films were characterized by XRD and the results shown that all of the ITO films deposited at the temperature above 160°C shown a polycrystalline structure. And as the substrate temperature increased, the optical transmittance and electrical conductivity were improved. It is also found that the increase of oxygen flux increased the optical transmittance of the deposited ITO films, however, at a given deposition rate, the electrical conductivity showed a maximum in a certain range of oxygen flux. ITO thin films with the resistivity of 1.65×10-4 Ω· cm and an optical transmittance of above 90% in the visible region were prepared at a temperature of 250°C by the given method.

In this paper, the stability of Al₂O₃ nano-particles in water were investigated at different pH values and different concentration of sodium dodecylbenzenesulfonate (SDBS) dispersant by measurement of the zeta potential and absorbency. The experimental results show that zeta potential is relation with absorbency, and the higher magnitude of zeta potential corresponds to the higher absorbency, and the better dispersion and good stability of the Al₂O₃-H₂O nano-suspensions. It is also found that the concentration of SDBS can significantly affect the value of zeta potential and absorbency. The experimental results show that for SDBS there is an optimizing concentration in the nanofluids which can induce high zeta potential and high absorbency, and that in 0.1% Al₂O₃ -H₂O nano-suspensions the optimizing concentration of SDBS is 0.09%, which has the best disperse results of the nanofluids.

Silicon is one of the most common materials used in optical micro-electro-mechanical systems (MEMS). For the optical applications the surface quality plays a vital role in the performance of elements, so the control of surface morphology, such as surface smoothing, is very important to produce optical MEMS elements with high reliability and high quality. The most commonly used etching methods such as reactive ion etching (RIE) always left damage layer on the etched surface leaving the surface with high roughness. In this paper 2.54GHz micro wave excited plasma was used to treat the silicon surface, and the different etching conditions of CF₄ and O₂ mixture were investigated. The surface quality after this down-stream plasma treatment was studied by atomic force microscopy (AFM) measurement.

Based on a model of coupling Maxwell's equations with the rate equations of electronic population, the spatial-distribution and spectrum-characteristics as well as amplified properties of defect modes such as lasing threshold, saturated output in a single-defect active photonic crystal are investigated through finite-difference time-domain method. Influences of the number of crystal periods and spatial profile on amplified feature are also analyzed. The results show that the lasing threshold and saturated output depend directly on the number of crystal periods and the spatial profile of defect modes; the defect mode with lower mode area has a low-threshold. Furthermore, the lasing threshold can be further reduced as the saturated output increases if the number of crystal periods increase. Such a feature is important for understanding of the interaction between optical gain and defect modes.

Using a time-independent calculation based on self-consistent transfer matrix method, we numerically investigate localized mode in a one-dimensional (1D) weakly disordered medium containing Lorentz dispersive material. The result show that the random medium containing dispersive media has frequency-dependent localized modes. Such localized modes strongly depend on dispersive parameters, such as transverse optical phonon frequency ω₀, oscillator strength Χ₀ and thickness of dispersive layer. The resonant frequency of such mode can be modified to shift by applying a dispersive medium. By this study, we will acquire some knowledge of localized mode in dispersive disorder medium; furthermore, this study suggests a method to realize tenability of localized mode, which is important for application of random laser.

We have tuned the lasing wavelength of a quantum dot laser diode (QDLD) by a thermal treatment. The InGaAs QDLD structure for 980 nm wavelength applications was grown by molecular beam epitaxy using the Stranski-Krastanov growth mode. The room temperature photoluminescence (PL) of a QDLD showed the ground state (GS) and excited state (ES) at the wavelengths at 993 and 946 nm, respectively. The 100 μm-wide and 4 mm-long broad area QDLD showed the lasing wavelength of 963 nm attributed to the ES of QDs with higher gain. After the thermal treatment at 800 °C for 3 minutes with 300 nm-thick SiO₂ capping layers, the PL intensity of the GS increased, which caused the enhanced GS gain. The enhanced GS gain is thought to the attribution to the decreased carrier trapping due to the defects quenching. As a result, we could control the lasing wavelength of the QDLD from a wavelength of 963 nm to a wavelength of 980 nm. Moreover, the performances of these QDLDs have been discussed. This post-growth technique can be used to enhance the performances of the optoelectronic devices based on quantum dot.

Based on the semiconductor laser whose spectral line with width is compressed to be less than 1.2Mhz, a system was designed to measure and improve the amplitude and frequency of the real-time microvibration with sinusoidal modulation. real-time microvibration measurement was executed without alignment problem in the interferometry; and low-frequency disturbance of environment could be eliminated. Suggestions were also given to consummate the system. The system also has resistance against the low frequency disturbance of the environment.

Self-assembled InGaN quantum dots are fabricated in a two-flow horizontal MOCVD reactor maintained at the pressure of 200 torr. The precursors were trimethyl-gallium (TMG) and trimethyl-indium (TMI) and ammonia (NH₃), and the carrier gas was N₂ and H₂. The optimum condition for periodically interrupted growth (PIG) mode was deduced to fabricate the InGaN quantum dots. NH₃ was supplied in PIG mode with the interval of 3 seconds and 5 seconds while TMG and TMI were supplied continuously. The carrier gas was N₂ in QDs growth, while H₂ in nucleation and buffer layer growth. The influence of number of periodic interrupted NH₃ on the structural and optical properties of InGaN quantum dots was investigated by AFM, FE-SEM and low temperature photoluminescence (LT-PL). The AFM images give the size of InGaN QDs with diameter of 20 ~ 50 nm, height of 3 ~ 10 nm and density of 10¹⁰ #/cm² ~ 10¹¹ #/cm². A strong peak at 362.2 nm (3.41eV) and broad emission peak in 435 nm (2.86 eV) were evolved in the photoluminescence measurement using Nd-YAG laser. The composition of QDs was estimated to be In_0.14Ga_0.86N from the relation between peak energy and indium content. Hence. The periodic interruption growth enables the fabrication of self- assembled InGaN QDs with high density and uniform size.

The thin films of transparent conductive aluminum doped ZnO have been deposited by the sol-gel process. In this study, important deposition parameters were thoroughly investigated in order to find appropriate procedures to grow large area thin films of low resistivity and high transparency at low cost for device applications. Experimental results indicated that the annealing temperature affected the crystal structure of the aluminum doped ZnO films considerably, but the controlling of effective doping concentration was the key point to achieve low film resistance by sol-gel process. It was adjusted by controlling the precursor concentration. Although the structure of our aluminum doped ZnO films did not have the preferred orientation along (002) plane, they had a high transmittance of over 87 % in visible region. In our experiments, the most suitable Al doped concentration was 1~4 mol%. The annealing temperature for the pre-heat treatment was 250 °C and post-heat treatment was 400-600 °C. The Al doped and undoped ZnO films are very uniform and compact. It is confirmed that the doping concentration and thermal treatment are important factor with electrical conductivity of ZnO films.

A novel process that combines interference lithography and ion beam etching is presented for fabrication of magnetic submicron structures and nanostructures in this paper. Instead of an antireflective coating, vertical standing wave patterns were removed using oxygen descumming process. A series of magnetic submicronmeter structures were fabricated on Co_0.9Fe_0.1 films by this technique. Fabrication of magnetic nanostructures was performed by using a high exposure dose and modifications in optimized development conditions. A thin Au film was deposited on the sidewall of the magnetic nanostructures to avoid the oxidation of Co and Fe. The effect of this method was confirmed by X-ray photoelectron spectroscopy (XPS). Hysteresis loops measured by a highly sensitive superconducting quantum interference device (SQUID) technique show the different magnetic properties of the magnetic patterns with different critical dimensions.

The multilayer structure composed of thin amorphous and nanocrystalline silicon carbide layers (a-SiC/nc-SiC) was prepared by the helicon wave plasma-enhanced chemical vapor deposition technique. Scanning electron microscopy and atomic force microscopy results show that the successive layers of a-SiC/nc-SiC is reproducible and the nanocrystalline grains can grow homogeneously for this multilayer structure. The optical emission property has been investigated by means of photoluminescence (PL) analysis. The red-shift of PL peak energy with increasing the excitation wavelength suggested that the optical emission originated from the quantum confinement effect of SiC nanocrystallites. A narrower PL band and smaller PL stokes-shifts are observed from the multilayer compared with normal nc-SiC film.

We systematically investigate realization of super narrow-pass-band and super narrow-transmission-angle filters with one-dimensional defective photonic crystal hetero-structures through the transfer-matrix method. The structure consists of a few different defective one-dimensional photonic crystal blocks. The influence of the relative bandwidth of the defective layer, the number of periods, and the ratio of index of the high index material to the low index material in the structures were studied. We find that when the relative width factor m and n of the defective layers are even numbers, relatively narrower pass-angle will be achieved. When the number of periods of the structures increases, the pass-angle will decrease exponentially. When the number of periods reaches 12, the pass-angle gets to be less than 0.002 degree. In addition, higher ratio of the two indices in the structures corresponds to smaller transmission angle and narrower wavelength pass-band.

Structural and optical properties of the B doped, P doped and B-P codoped silicon nanocrystals have been investigated using first-principles calculations. It was found that the codoped system tends to reduce structure distortion around B/P impurities compared with B/P single doped systems and shows a decreased energy band gap compared with undoped system due to there being electronic compensating effect. In addition, the spatial behaviors of density of states indicated that codoping possesses a tendency of confining the electrons and holes around the B/P impurities, which suggests the possibility of increasing electron emission transition rates between donor and acceptor. Moreover, the dielectric functions calculation demonstrated that the optical absorption of codoped silicon nanocrystals have the characteristic of the energy band gap being redshifted with respect to the undoped case together with peak appearing at lower energy side.

In this paper, a novel compact optical modulator based on silicon photonic crystals /nano-montmorillonite is proposed. The two-dimensional silicon photonic crystal with triangular lattice and a line defect waveguide formed by a missing row of air holes in the Γ -K direction. The lattice constant is a, and the diameter of the holes is d=0.4a. The holes are filled with the nano-montmorillonite electrorheological fluid, which is made of nanometer sized nano-montmorillonite. The light modulation mechanism of the novel modulator is based on a dynamic shift of the photonic band gap. We have investigated its light modulation performance by using the finite-difference time-domain method. The numerical results show that an excellent optical modulator at a wavelength of 1550nm is achieved. The novel modulator has a high extinction ratio (close to -40dB) and small size (around 10μm). It is very suitable for forthcoming photonic integrated circuits.

On metallic gratings with very narrow slits, the Fabry-Perot-like phenomenon has been found in the SP resonant transmission: Transmission peaks appear periodically according to the increment of grating depth. We study the phenomenon by setting constants of the structure to be at nanometer scale. The rigorous coupled-wave analysis method (RCWA) has been used in this work. The grating structure we examined is composed of silver. Slits are filled with dielectric. For silver, its plasma wavelength λp=110nm. We study the gratings with period of gratings d=3λp, the grating depth h=2.5λp, width of slits is 0.22λp, and slits on the grating is filled with GaP which refraction index is 3.7. Under this situation, there is no excited peak at the wavelength theory predicts. Next we have investigation on the transmission of the SP resonant mode. Wavelength of normally incident TM-polarized plane wave equals period of gratings. It can be seen from the zero-order SP resonant transmission versus the grating depths, that there is no Fabry-Perot-like phenomenon upon the wavelength calculated from the theory, which appears evidently at greater geometry. Transmission value falls quickly via grating depth increases. Fabry-Perot-like phenomenon is caused by energy transmission in the slits, but nanometer scale slits will cut off the energy transmission in the slits. It's concluded that the surface plasmons execute negative effect on transmission anomalies when the grating dimension is at nanometer scale. It's useful for the fabrication of the sub-wavelength optical element.

A new, simple and efficient method is presented for calculation of the ground and a few excited states of Hubbard chain nanostructures. By using this method, the photoemission spectral function for organic charge transfer salt TTF-TCNQ, is calculated. For a chain with maximum 70 sites the result is in good agreement with the previous works but there is a difference for further number of sites in the chain, which is discussed in the text with all the specifics. We also show that a source of errors in density matrix renormalization group method for a one dimensional chain is the deficiency of the matrix product scheme for generating the desired states of the linear chain.