GaN materials have wide application prospects in the fields of high frequency, high power, high temperature and high-density integrated electronic devices etc, which is forefront and hot spots in global semiconductor field. In recent years, great progress has been made in the research of low contact resistivity of metal/GaN Ohmic contact. However, the metal/GaN Ohmic contact is still one of the most important factors that restrict the development and application of GaN devices. The introduction of laser technology provides a new method for the realization of Ohmic contact of metal /GaN. Investigation of Ohmic properties improvement of GaN materials by laser irradiation is summarized. Research progress of the excimer laser irradiation on the hole concentration change and improvement of GaN materials Ohmic contact properties is introduced. The low Ohmic contact resistivity scheme for GaN is discussed in order to explore the direction of better metal/GaN Ohmic contact.

The imaging model for aerial long range oblique photography(LOROP) camera is the basis of geometric calibration, atmospheric refraction and assemble error correction. Through analysis of the imaging principle for LOROP camera, eliminating the moving photography center, the strict imaging model for LOROP with physical meaning and solvability is constructed, and its correctness is verified by simulation, which provides a reference for the related research. The oretical analysis and simulation measurements show that the system whose optical system and scanning mirror sweep together has the advantage of no image-rotation. The control situation of LOROP camera is analyzed theoretically. Results show that the cross-track scanning position and image motion compensation speed are nonlinear process which is positive correlated with the aviation speed and height.

In order to solve the inconsistent problem of traditional image inpaint process, an adaptive multiple matched patches random search image completion method based on narrowband optimization is proposed. Damaged images are decomposed by wavelet transformation to obtain low and high frequency sub-images with different resolution. The size and number of matched patches are adaptively calculated according to color and structure information of unrepaired patches along the damaged boundary of each sub-image. Matched patch sequence is found randomly based on the minimum heap, and the narrowband model is used to optimize the damaged boundary. The damaged boundary is inpainted from outside to inside until the damaged area is completed. The final inpainted result is restructured using the wavelet reconstruction algorithm. Experimental results show that the completion result with the proposed method has better visual consistency compared with the existing methods.

A single image dehazing method based on recursive bilateral filtering is proposed. Combining with the boundary conditions of scene radiance, the dehazing model is applied to estimate the initial value of the atmospheric veil, and recursive bilateral filtering is applied to refine the initial value in order to obtain the high-quality clear image. Based on several neighboring frames information around current frame of the video-image, its globe atmosphere light is estimated. The atmospheric veil is filtered across each frame of the video-image with recursive bilateral filtering. The proposed method is extended to video-image dehazing, and the video-image dehazing result with temporal coherence is obtained. The affinity propagation algorithm is applied to obtain sampling points of haze images for accelerating the dehazing processing. Compared with the existing methods, the proposed method can get better dehazing results for the haze images with many edge features and complex scenes.

Based on the minimum energy error, the disparity image of the left and right views is obtained, and the steerable pyramid decomposition which has four scales and twelve orientations are carried on the left, right views and their disparity image. Each image can get one high frequency sub-band and fourty-eight directional sub-bands. The bivariate generalized Gaussian distribution fitting is carried on fourty-eight pairs of directional sub-bands corresponding to the decomposition of left and right views. Their shape and scale parameters are extracted, and across scales, spatial correlation statistical features from all orientation sub-bands are extracted. These features are input to support vector regression (SVR) to train and predict the stereo image quality score. Results show that the performance evaluation index of the quality evaluation model in LIVE 3D database, Spearman rank order correlation coefficient (SROCC), linear correlation coefficient (CC) are all above 0.93, which has good consistency with the subjective evaluation of human.

Based on the simplified Weiss-Tabor-Carnevale (WTC) algorithm and symbolic computation, Painlevé properties and analytic solutions of the variable coefficient nonlinear Schrdinger (NLS) equation are investigated, which involves four arbitrary functions of space-time. Among the four variable coefficients of the equation, the first two are two-order dispersion of longitudinal distance and nonlinear coefficient respectively, and the last two are the real and imaginary parts of the fiber loss factor. Relationship among the four variable coefficients are derived with WTC method when the equation is Painlevé integrable. Three special forms of rational function solutions are derived with Painlevé truncation method, and the partial solutions of the equation are obtained by using the variable separation method. The obtained results are the extension of existing conclusions.

Lie symmetry theory is an effective method to find exact solution of mathematical and physical equations. The symmetry and reduced equations of Brinkman model are derived based on Lie symmetry theory. Some new exact solutions of the equation are obtained by solving the reduced equations, including variable separation and traveling wave solutions. Some variable separation solutions contain the effect of anisotropy of thermal conductivity on temperature. These solutions and traveling wave solutions are not reported in the existent literature, and they can more realistically reflect the natural convection flow in Brinkman model.

Aiming at (2+1)-dimensional Sawada-Kotera equation, the new non-traveling wave periodic and kink solutions with an initial value perturbation parameter and an arbitrary function of time are obtained combining Lie symmetry group reduction method, perturbation Painlevé truncation expansion method and homoclinic test method. Results show that the equation has rich dynamic connotation, and provides an analytical tool to explain some physical phenomena.

A steady-state mechanical modes squeezing scheme using a ring-cavity optomechanical system is proposed. The system consists of a fixed mirror and two oscillating mirrors. The oscillating mirrors can be regarded as non-harmonic oscillators with cubic nonlinearity. Cavity optical field driven by input laser produces radiation pressure on the oscillating mirrors. The steady-state amplitude of the optical field and mechanical modes in the cavity and squeezing properties of the mechanical modes are investigated. Results show that the steady-state amplitude increases with the increasing of driving power. The mechanical modes can be squeezed in a large range of parameters, and the squeezing can be enhanced by increasing the cubic nonlinearity strength and power of the driving laser, or adjusting appropriately the frequency detuning between the driving field and cavity field. The squeezing is robust to thermal phonon noise.

A new multi-control Toffoli(MCT) gate exchange rule is proposed in reversible MCT circuits. Reduction and moving rules of MCT gate sequence are given based on the proposed rule, and a more general reversible MCT circuit simplification algorithm is realized. Effectiveness of the simplification algorithm is verified by specific examples and experimental results of all three variables reversible functions, and it can further reduce the gate number and quantum cost of the reversible circuit. Compared with the existing similar rules, the proposed MCT gate exchange rule has no constraint conditions, and it has stronger applicability, which improves the simplification results of reversible MCT circuits.

Combined with the actual demand of artificial vote in real life, a new secure voting protocol based on quantum secret sharing is proposed. In the protocol, four particles of each group of four-particle GHZ-state are delivered to the voter Alice, verifier Bob, signatory and internal auditor Charlie and external auditor Trent respectively. Alice measures the particles of her own to vote her message out. Charlie, Bob and Trent complete the signature, verification and audit work by measuring their own particles. Compared with the previous protocols, the roles in the proposed protocol are comprehensive and they can be substantially involved in voting related activities. It avoids the use of complex quantum fingerprint function, so it is easy to implement technically. Because of the dual supervision, the authority of the election result will be highly recognized by the internal and external of the ballot management center.

A visibility lidar for the civil aviation airports is designed and developed. The observation experiments are carried out for six months continuously, and the results are compared with the atmospheric transmittance meter, atmospheric forward scattering meter and artificial observation results which are used in airports currently. Results show that the developed DSL-V backward scattering visibility lidar can meet the technical requirements of International Civil Aviation Organization (ICAO). When the visibility ranges from 0 to 600 m, the detection error is less than 11.3% (Absolute error of visibility is less than or equal to 26 m). When the visibility ranges from 600 m to 1500 m, the detection error is less than 8.2%. When the visibility ranges from 1500 m to 10000 m, the detection error is less than 14%.

In order to improve the spectrum utilization of fiber communication system, the dense wavelength division multiplexing (DWDM) system of 8-level amplitude and differential phase-shift keying (8APSK) and differential 8-level phase-shift keying (D8PSK) are set up. Simulation results show that when the probe channel is 8APSK, the optimal incident average optical power increases with increasing of 8APSK amplitude modulation index. Whether it is 8APSK or D8PSK modulation, four-wave mixing noise has little influence on the system performance when the incident average optical power is optimal. While it exceeds the optimal value, the influence increases rapidly. For the discussed DWDM system, the transmission performance of 8APSK signal with amplitude modulation index optimization is obviously better than that of D8PSK, which is mainly attributed to the better tolerance of total nonlinearities for the former.

The vertical optical coupling of AlGaN/GaN quantum well mid-infrared photodetector is enhanced by using two-dimensional gold grating structure, which is not sensitive to the polarization of incident light source. The electric field distribution and energy flow in the detector structure are calculated by the finite element method (FEM). It is found that the effective electric field intensity of quantum well with two-dimensional gold grating is two orders of magnitude higher than that of Si3N4 grating. It is mainly due to the surface plasmon polariton (SPP) excited at the interface of gold grating and AlGaN, which strongly changes the direction of light energy flow and electric field vibration. No matter how the light source polarization is, when the vertical incident electromagnetic wavelength is 4.7 μm, electric field intensity E is 1 V/m, the effective |Ez|2 in quantum well region reaches 0.7 (V/m)2, which provides a solution to realize the focal plane array of AlGaN/GaN quantum well mid-infrared photodetector.

Surface charging level of epoxy resin materials applied to spacecraft surface at different temperatures is investigated. By setting different beam density, effects of temperature and electron beam density change on surface charging level of epoxy resin are investigated. Results show that when the beam density is 0.5 nA/cm2 and 1 nA/cm2, the surface charging balance potential of epoxy resin shows the trend of decreasing first, increasing and then decreasing in the temperature range from 243 K to 363 K. When the beam density is 2 nA/cm2, the variation range of surface charging balance potential of epoxy resin is not big. It can be found that when the beam density is small, effects of temperature on surface charging balance potential are stronger. The greater the beam density is, the weaker the effect of temperature on surface charging balance potential will be, so the surface charging balance potential of epoxy resin is more stable.

A new mechanism to achieve optical delay is proposed. A compound waveguide with unidirectional boundary loop and unidirectional air waveguide is constructed. When the electromagnetic wave propagates through the boundary loop, its one-way transmission and the constructive interference effect make the electromagnetic wave around these loops to achieve the perfect transmission. These loops lead to optical delay because of the enlarged propagation distance. The unique feature of the composite waveguide is that it has compound functions, such as optical delay, one-way transmission and overcoming scattering loss. The frequency-domain and time-domain simulation demonstrates the perfect transmission and time delay function, respectively.