Compared with traditional bonding methods, wafer direct bonding at low temperature has the advantages of low bonding loss, no intermediate layer pollution and no external electric field assistance. It has important application potential in power semiconductor optoelectronic and power electronic devices, high power solid-state lasers, MEMS, optoelectronic integration and other fields. In this paper, the physical and chemical mechanisms of hydrophobic bonding, hydrophilic bonding and plasma-activated bonding are introduced emphatically based on the development of low temperature direct bonding technology. The technological processes of low temperature direct bonding and the characterization method of bond strength are described systematically, the development trend of low temperature direct bonding technology is discussed, and the improvement and innovative application of low temperature direct bonding technology are prospected.

A metamaterial-based terahertz amplitude modulator is proposed with the structure consisting of an open "bow" shaped metamaterial structure, a high electron mobility transistor, an oblique cross feeder and a silicon carbide substrate. Whether the openings of the "bow" shaped metamaterial structure are connected or disconnected will produce different responses to the terahertz waves passing through the structure. The effect of connecting and disconnecting the openings can be simulated by adding high electron mobility transistors to the openings of the "bow" shaped metamaterial structure. When no bias voltage is applied to the gate of the transistor, the opening of the metamaterial structure is equivalent to conduction, and the transmission coefficient to terahertz waves is high; when bias voltage is applied to the gate on the transistor, the opening of the metamaterial structure is equivalent to disconnection, and the transmission coefficient of terahertz waves is low. The simulation results show that the transmission coefficient of the modulator is 0.579 at 0.22THz when no bias is applied to the transistor gate, while it is 0.040 at 0.22THz when bias is applied to the transistor gate. The modulation depth of 93% is obtained by the equation, and the modulator is insensitive to x- and y-polarized incident waves. Meanwhile, the operating principle of this terahertz modulator is studied by analyzing the electric field distribution and surface current distribution at 0.22THz. The terahertz modulator designed in this paper is characterized by high modulation depth, simple structure and easy processing, which has a broad application prospect in the field of terahertz communication.

The infrared bolometer based on Mn-Co-Ni-O (MCNO) films with thermal isolation structure is designed and fabricated by wet etching process. Test results indicate that, the thermal conductance of the bolometer with thermal isolation structure is greatly reduced and it is 1.37mW/K under vacuum, which is only 1/20 of that without thermal isolation structure. The V-I measuring experiments and curve fitting prove that the thermal conductance of MCNO increases with the temperature. The bolometer responsivity is significantly enhanced by applying the thermal isolation structure, and the typical value is 50.5V/W at the modulation frequency of 30Hz under the bias of 36V, which is 10 times of that without thermal isolation structure. The feasibility of fabricating bolometer based on MCNO films with thermal isolation structure is demonstrated.

A GaN-based p-i-n diode with vertical structure was fabricated with epitaxial method by using high quality free-standing GaN substrate. Based on studing the material structure, impurity concentration and current-voltage characteristics, the key factors affecting the performance of the vertical structure device were analyzed. Experimental results indicate that the roughness of the surface will cause the irregular shape of the annular structure, which plats a negative effect on the ohmic contact and performance of the vertical structure device. In addition, during the growth process, a variety of impurities will gather at the interface and form a planar leakage channel, which will dominantly limit the performance of the device.

A thin-walled cylindrical liquid temperature and pressure sensor based on distributed sensing technology was designed. The sensors are packaged with stainless steel 316L and beryllium bronze C17200, which have corrosion resistance, good elasticity, and a large thermal expansion coefficient. The finite element simulation software ANSYS Workbench was used to simulate and analyze the pressure and temperature characteristics of the packaged sensor, and the radial strain of the device was obtained, and the relationship between the Brillouin frequency shift and the pressure and temperature was analyzed. The simulation experiment shows that the pressure sensitivity and temperature sensitivity of the sensor using the beryllium bronze C17200 package is higher. The pressure sensitivity can reach 11.1MHz/MPa and the temperature sensitivity can reach 2.56MHz/℃ in the range of 0~12MPa and -5~40℃. Compared with ordinary single-mode fiber, it is increased by 7.4 times and 1.7 times respectively.

A self-adjustable CMOS charge pump phase-locked loop (CPLL) circuit with accelerated compensation for high-speed image sensors is designed. Regarding to traditional PLL topology, a "dual-mode" logical clock-controlled and low-power accelerated charging compensation module is added to achieve synchronize optimization in locking time and power consumption. Based on the 180nm/1.8V CMOS process, the circuit design and performance simulation are implemented. The results show that, based on the proposed acceleration compensation scheme, the improved PLL can meet the requirements of high-speed image sensoring application with low noise, low power and high frequency. When a reference signal of 1GHz is input, the proposed voltage-controlled ring-oscillator reaches 0.55~2.82GHz with 2.27GHz frequency range, phase noise is -98.149dBc/Hz@1MHz, locking time is shortened to 5.2μs, average power consumption is only 1.98mW, and the jitter noise in output can be as low as 2.81μV/Hz@1MHz. The proposed PLL has significant superior circuit in power and locking time compared with some other design cases.

Based on the requirements of miniaturization, intelligence and low power of CO2 infrared gas sensor, a special MEMS infrared source chip for CO2 detection is innovatively proposed with the center temperature of 407℃. The chip is a micro hot plate with X-type suspending bridge structure. And the internal heating area is tungsten heater with ring routing structure, SiO2 and Si3N4 dielectric thin films as the mechanical support film. The infrared source chip is optimized with uniform temperature distribution in heating zone, short thermal response time and low power by the finite element simulation analysis. The chip is fabricated by 10.16cm (4inch) MEMS process. The results show that, the temperature of this chip can quickly rise to 407℃ within only 24ms, the power consumption is as low as 46mW, the working voltage is 2.85V, and the current is 16.2mA. The chip has the advantages of fast thermal response, low power dissipation and high integration.

In this paper, a theoretical model on LD unidirectional side-pumped laser module has been constructed. Combining ray tracing and finite element simulation method, these calculation formulae on pump efficiency and distribution uniformity of light field in the crystal were derived. The effects of LD tangential displacement, radial angle deviation and crystal absorption coefficient on the pump efficiency and the uniform distribution of pump light in the crystal were also numerically analyzed. The results show that, with the increase of absorption coefficient, the distribution uniformity of light field in the crystal will decrease gradually. Maximum pump efficiency up to 93% can be achieved by optimizing the deviation of LD displacement and radial angle. The research results have certain reference value for optimization design and experimental study of the high power LD unidirectional side-pumped laser module.

A closed-loop resonant fiber optic gyroscope system using a fixed frequency narrow linewidth laser as the interference light source is proposed. The system uses a phase modulator to perform frequency shift control of the interference light to complete the tracking and locking of the resonant frequency in the counterclockwise direction of the resonant cavity. In this paper, a Simulink model of the gyro system was established and the output characteristics of the gyro were simulated at different speed points. The results show that the lock time of the counterclockwise resonance frequency in the range of ±200(°)/s is less than 15ms, and the gyro scale factor nonlinearity is 241ppm. Compared with the closed-loop resonant fiber optic gyroscope system using traditional frequency tunable narrow linewidth lasers, the frequency lock time and scale factor nonlinearity of the two systems are basically the same. This research provides theoretical and data support for the realization of low-cost closed-loop resonant fiber optic gyroscope system.

Photonic crystal circulators with the structure of six-port and eight-port were designed based on two-dimensional triangular lattice and square lattice photonic crystals, respectively. The circulators consist of a photonic crystal waveguide composed of silicon rods and ferrite dielectric rods defects. The designed six-port circulator has only one ferrite rod at each waveguide junction, which can effectively reduce the loss; the eight-port circulator has multiple ferrite rods added at the waveguide junctions to effectively improve the isolation. The transmission of electromagnetic waves in the circulator is simulated and verified by using the finite element method. The results show that the isolation of the six-port circulator is 22~38dB, and the isolation of the eight-port circulator is 21.7~40.5dB. The designed multi-port circulators have the advantages of simple and compact structure, high isolation and low loss.

In this paper, Al-doped ZnO (AZO) films with better photoelectric properties were prepared by the dual-target co-sputtering method. Various technical methods such as X-ray diffractometer, Hall tester and SEM were used to study the influence of different Al sputtering power and rapid annealing conditions on the performance of AZO film. It is found that the AZO films present the best performance when the Al sputtering power is 15W and the annealing temperature is 400℃. When the Al sputtering power is 15W, its lowest resistivity is 6.552×10-4Ω·cm, and the average transmittance in the visible light band (400~700nm) exceeds 92%. With the increase of Al sputtering power, the transmittance in the visible light band gradually decreases, while the transmittance in the infrared band (2.5~20μm) gradually increases, and the maximum value reaches 40%.

In this paper, the static response of a thermal piezoelectric semiconductor (PSC) beam with flexural deformation is studied with a differential operator method. The analytical solutions of the deflection, electric potential, carrier density, temperature, shear force, bending moment, electric displacement and electric current density are obtained. The effects of temperature on the electromechanical behaviors of n-type ZnO piezoelectric semiconductor cantilever beam are discussed. The numerical results show that the temperature can significantly affect the electromechanical properties of PSC beams. It causes sudden changes of the electric potential, carrier density, electric field, and electric displacement in high temperature regions, while smaller changes of the deflection, shear force and bending moment. These effects are mainly induced by the polarization charges of pyroelectric effect.

The experiments of surface processing were performed on AlN ceramic by femtosecond laser, and the effects of laser energy density and scanning speed on the surface morphology and size were analyzed. Considering the processing quality and efficiency, the optimized parameters of energy density of 10~14J/cm2 and scanning speed of 20~30mm/s were selected. Based on this, the spiral scanning track was applied to drill holes on AlN ceramic. The round, square and runway holes without micro-crack and edge chipping were successfully realized. This study verifies the possibility of femtosecond laser processing high-quality holes with multi-shapes. It promotes the application of laser drilling technology for hard and brittle materials in the field of semiconductor power devices.

Considering the influence of convective heat transfer, a mathematical model of heat and mass transfer was established for the growth system of large-size SiC single crystal based on physical vapor transport method. The distribution of temperature field and gas phase flow field in the growth system was studied by numerical simulation. The results show that the temperature, temperature gradient and heating efficiency in the crucible will gradually decrease with the increase of coil turn spacing and coil diameter. The rotating crucible can effectively solve the non-uniformity of temperature field caused by the coil spiral shape. By continuously adjusting the relative position between the coil and the crucible, the optimal temperature field environment for high quality crystal growth can be ensured. In addition, the increase of the inner diameter of the crucible will aggravate the natural convection effect.

Based on the constructal theory and the numerical calculation method of multi-physical field coupling, the multi-chip module was established with uniform heat generation under natural convection. By taking the maximum temperature, maximum stress and maximum deformation as optimal objects, and taking the number of chips and the ratio of chip length to width as the design variables, the influences of chip layout evolution on the system performance are discussed under the total area constraints of printed circuit board and chips. The results show that the constructal optimization is an 8-chips layout with a chip aspect ratio of 2.1 under different performance indicators. The maximum temperature, maximum stress and maximum deformation of the multi-chip module can be reduced by up to 16.5%, 28.3%, and 26.9%, respectively. The effect of two degree of freedom optimization on the number of chips and the ratio of chip length to width is obviously better than that of single degree of freedom optimization only on the ratio of chip length to width.

A novel and high nonlinear photonic crystal fiber structure for supercontinuum generation was designed, and the size of the air holes in the cladding layer of the fiber is concave. The diameter of the innermost air hole d1 and the diameter of the outermost two air holes of d5 and d6 are set to a larger value to obtain high nonlinearity and low loss, respectively. In order to reduce the difficulty of optical fiber fabrication, the diameters of the second to the fourth air holes are set to be the same. Based on multipole method, the effects of air hole spacing Λ and air hole diameter on dispersion, nonlinear coefficient and loss of PCF are analyzed, and the optimal structure parameters are designed. The simulation results show that the double zero dispersion points of the fiber are 798 and 1260nm, respectively, and the maximum dispersion is 71.6ps·nm-1·km-1. In the wavelength of 0.72~1.3μm, the dispersion slope of the PCF structure is less than 0.81ps·km-1·nm-2, the nonlinear coefficient is 153.2W-1·km-1 at 780nm, and the loss is 3.1×10-3dB/km at 800nm.

Since the internal defects of the through silicon via (TSV) three-dimensional package are hidden deeply inside the device and the package, they are difficult to be detected with conventional methods. However, TSV 3D packaging defects can show regular external characteristics under the condition of thermo-electric excitation. Therefore, TSV 3D packaging internal defect detection can be achieved by identifying these external features. In this paper, the combination of theory and finite element simulation were used to compare the temperature distribution of normal TSV and typical defective TSV, and significant differences were presented for defect identification. The analysis results show that among the three typical defects, the difference in temperature distribution between TSV with gaps and normal TSV is the smallest, the second is TSV with bottom cavity, and the largest difference is TSV with filling missing. It can be seen that by detecting the external temperature characteristics of the TSV package under thermo-electric coupling excitation, the internal defect diagnosis and location of the TSV three-dimensional package interconnect structure can be realized.

The ink containing carbon nanoparticles (CNP), carbon nanotubes (CNT) and TiN nanoparticles were chosen as raw materials, the high voltage electrostatic spraying technology was used to deposite CNT/CNP-TiN coatings on aluminum substrate. The effects of electrostatic voltage, spraying height and spraying amount on the optical absorption properties of the coatings were studied. The results show that when the electrostatic voltage is 9kV, spraying height is 30mm and spraying amount is 35μL, CNT/CNP-TiN coating exhibits excellent optical absorption performance, and the average absorption in the range of 400~1400nm reaches 97.1%. Honeycomb clusters are constructed by TiN nanoparticles, CNT and CNP. Optical cavities of several hundred nanometers to micrometers formed between the clusters and optical cavities of several tens to several hundred nanometers within the clusters can trap lights with different wavebands, and broaden the absorption bandwidth. In addition, TiN nanoparticle, CNT and CNP have good light scattering effect, and most of the scattered light is trapped by the optical cavities, so as to further improve the absorption.

For the high-efficiency thermal conductivity of heat pipes and the unique advantages of thermoelectric cooling, such as noiselessness, environmental protection, and rapid cooling, a new structure of heat pipe-cooled thermoelectric water-chiller is proposed. Based on the finite-time thermodynamics theory and considering various thermoelectric effects including the Thomson effect, a detailed calculation model is established. The influence of key operating parameters and design parameters on the optimal current and optimal performance of the device is analyzed. And the optimal interval of the input current and the optimal interval for coordinating the maximum cooling load and the maximum coefficient of performance (COP) are given. The optimization results show that when the temperature difference is 20K and the current is 2.5A, the maximum cooling load and maximum COP are improved by 55.3% and 47.0% after optimization, reaching 29.49W and 1.47, respectively.

Based on the first principles, the materials studio software was used to simulate the energy band structure, density of states, and optics properties of 2H-MoS2. The results show that MoS2 was an indirect band gap semiconductor with a band gap of about 1.25eV; the material had a certain absorption in the ultraviolet to visible wavelength range, and the absorption coefficient decreases with the increase of wavelength. Raman spectra showed E12g and A1g vibration modes at 375 and 400cm-1, respectively. Typical diffraction peaks such as (103) and (101) appeared at the positions 39.5° and 33.5°. Magnetron sputtering method was also used to prepare MoS2 films with different thicknesses on a quartz substrate in this paper. It was found that the film had (101) preferred orientation, E12g and A1g were also presented at 375 and 407cm-1 in the Raman spectrum. As the film thickness increased, the transmittance of the film in the visible light band decreased, and the optical band gap shifted toward longer wavelengths. The simulation results were basically in agreement with the experimental results.

The production process of precision molds used in cylindrical microlens nanoimprint was simulated, and ultra-precision cutting technology is one of the effective means for processing precision imprinting mold. Based on the Johnson-Cook constitutive model, the finite element analysis method was applied to simulate the relationship between the cutting parameters and the cutting force during the ultra-precision cutting process, and the preferred cutting parameters were obtained. Experimental results show that the cylindrical microlens array mold can obtain good cutting effect using the preferred cutting parameters. The surface precision RMS value and the surface roughness Sq of the mold after cutting reaches 19 and 4nm, respectively.

Fine guidance sensor (FGS) in the space astronomical telescope can realize high-precision measurement of attitude information for the precision image stabilization system. The imaging effect of the CMOS image sensor (CIS) directly affects the calculation accuracy of FGS. However, the CMOS imaging device has the best readout range in actual operation, and the linearity of the incident ray intensity and the number of photo-generated electrons beyond this range is low, and the effective star points cannot be obtained to meet the centroid coordinate solution of the later stage. In order to solve this problem, a method for estimating the best integration time of different magnitude is proposed and the integration time can be used as the main basis for the selection and adjustment of detector parameters. The measurement results show that both the dark current of the sensor and the RMS noise will increase with the increasing integration time. According to the star facula distribution model, the best integration time range of commonly used stars is calculated. Combining with the star spot distribution, it is concluded that there are about seven stars in the field of view of 7-magnitude stars, which demonstrates the detection ability of small CMOS devices for star spots.

Due to the scale as well as the resolution between infrared and visible images are quite different, the number of images feature points is insufficient and their distribution is nonuniform, which makes the existing algorithm usually fail to register the two heterotopic images, thus an improved registration algorithm is proposed by using rolling guided filter and phase information. Firstly, the rolling guidance filter is used to construct the scale space, so as to keep the image edge information as much as possible without increasing the time consumption. Then an improved Shitomasi algorithm was proposed, which extracts strong corner points with scale invariance and uniform distribution. In the stage of feature description, a new weighted function was given to spread the frequency to obtain more significant phase congruency and it’s more accurate for the feature description of blurred images. The experimental results show that the registration method can still achieve accurate registration for infrared and visible images with 9-fold scale difference, and the RMSE of the multiple image pairs remains within 2-pixel error.

Aiming at the problems of low registration and superposition accuracy of ultraviolet image and visible image and large deviation of corona discharge location in ultraviolet imager, a UV and visible image registration and fusion method was proposed based on the GoogLeNet model, Wavelet Transform (WT) and Canny operator, and it was applied in highly sensitive UV imagers. First, by introducing the idea of migration learning, the pre-trained GoogLeNet model was used to autonomously mine the characteristics of visible light and ultraviolet images. Then, the extracted features were input into extreme learning machine (ELM) as predictive variables, and supervised model training was guided by spatial transformation parameters to achieve high-precision UV and visible image registration. Finally, the multi-resolution analysis and edge detection of the registered image were carried out by using two-dimensional wavelet transform and Canny operator to realize the image fusion without UV information loss. The experimental results show that the proposed method has high registration accuracy of UV and visible images, completing good fusion effect and engineering applicability.

In order to solve the problems of scrolling grayscale images of a vertical pixel count higher than 768 using digital micromirror device (DMD) in direct laser writing system, the data transmission and storage and display driving technology of the control circuit was studied. The improvement in image data transmission mode was realized based on the rich logic resources in the FPGA which were used to split the data and convert the bit-width through shift registers. In addition, an interval storage method was proposed to realize the storage of large-size image data. Based on this method, the data can be read during the scrolling display of grayscale images. The workflow of the DMD display device was simplified and the efficiency was promoted by saving the operations of bit-plane splits and images segment in the upper computer. The experimental results show that the system can complete the scrolling display of grayscale image with 419.6Hz.

The surface shape accuracy of the transparent objective lens in the lithographic projection objective is one of the key factors affecting the imaging quality of the optical system, and the support deformation is a very important factor affecting the surface shape accuracy. In order to improve the reproducibility of the optical inspection of the large-aperture lens, an integral flexible support structure was designed, and the influence of the number of shrapnel and various dimensional parameters on the surface accuracy and reproducibility of the lens under the action of gravity was analyzed. The analysis results show that: increasing the number of shrapnel, reducing the distance between the support and the center of the lens and increasing the thickness of the shrapnel can reduce the deformation of the lens. The reproduction accuracy can be improved by shortening the length of the shrapnel, increasing the thickness of the shrapnel and the number of shrapnel. According to the analysis of the relationship between the influence factors and the reproducibility, the reproducibility under the optimized parameters is 0.21nm rms, which can meet the high-precision surface shape requirements of the lens in the deep ultraviolet lithography projection objective.

To address the problem that the dark channel prior algorithm will produce artifacts and residual fog, a dehazing method was proposed based on double dark channel and Gaussian weighting, which use superpixel block filtering and median block filtering to obtain two layers of dark channels, respectively. Then a pixel-level fusion was performed on the two-layer dark channels and a Gaussian weighting function was constructed for enhancement. The white area that contains the sky was extracted based on the HSV color space and the average value of the brightness component of the top 10% of the pixels in the white area was taken as the atmospheric light. Experimental results demonstrate that the proposed algorithm can preserve details and remove residual fog while improving artifacts.

A monitoring experiment system of submarine cable vibration signal was set up based on Brillouin optical time domain analysis (BOTDA). The vibration signals of submarine cable under three working conditions of anchor smashing, scouring and friction were obtained. The TSA-VMD-MPE method was proposed to reduce the noise of vibration signal. The tunicate swarm algorithm (TSA) was applied to optimize decomposition level and penalty factor of variational mode decomposition (VMD) to obtain intrinsic mode functions (IMF) components. The correlation between the IMF and original signal, and the IMF variance contribution rate were considered comprehensively to determine the multi-scale permutation entropy (MPE) threshold to reduce the noise of the vibration experimental signal. The experimental results show that the signal-to-noise ratio of the three kinds of submarine cable vibration signals is improved by 12.0296dB on average. The proposed MPE threshold determination method was applied to EEMD and CEEMD algorithms, and good noise reduction effect was obtained.