Organic photodetector (OPD) with high sensitivity has broadband response from visible light to near infrared (NIR) and excellent overall device performance. It plays a very important role in various applications including high-quality biological imaging. In this paper, Silvaco TCAD used to simulate a broadband organic photodetector whose active layer was made of a mixture of a broad band gap polymer PBDTTT-C-T as a donor and a newly developed fused octacylic small molecule FOIC as a receptor. The simulation results show that the dark current density, the external quantum efficiency and the lowest detectable light intensity ability of the device reach high standard and fit well with the experiment data. In view of this, it is believed that the parameters used in the simulation process have good reliability and value, which can provide useful reference for the simulation and research of the same type of photodetector.

Quantum well FPA with reflection coupling structure is relatively easy to fabricate compared with the grating coupling structure. In order to explore whether the RC structure could replace the GC structure in the small size range, the MEEP, a software which is based on the FDTD, was used to construct the 3 pixels model of GC structure and RC structure GaAs/AlGaAs quantum well infrared FPA. According to the simulation of the internal optical crosstalk problem of the device, it is verified that when approaching the diffraction limit, the anti-crosstalk effect of FPA with RC structure is stronger than that of RC structure when the pixel’s size is between 5~7 μm and 8.5~10 μm, while GC shows better performance while the pixel’s size is between 7~8.5 μm and 10~12 μm, and the anti-crosstalk ability of the two structures shows close performance in the range of 12~15 μm. For the quantum well FPA with 15 μm pixels and RC structure, the influence of reflection angle, etch depth and the period of quantum well on its performance of fighting against the crosstalk was explored.

The theoretical model of thulium-doped fiber laser based on the simplified two-energy laser system and uniform spreading theory model was established, using the atomic rate equation and power transfer equation. Taking the ring cavity thulium-doped fiber laser as an example, the relationship between its output power and wavelength tuning range and cavity loss, thulium-doped fiber length, output coupling ratio, pumping wavelength and pumping power, etc., was investigated through Matlab programming numerical simulation. The numerical simulation results show that reducing the laser cavity loss, increasing the pump laser power and optimizing the thulium-doped fiber length can improve the output power and increase the wavelength tuning range of thulium-doped fiber laser, while increasing the output coupling ratio can improve the laser power but reduce the wavelength tuning range. After parameter optimization, the wavelength tuning range of the thulium-doped fiber laser can reach 528 nm (1 660~2 188 nm) by increasing the pump laser power and optimizing the thulium-doped fiber length at a total intra-cavity loss of 3 dB and an output coupling ratio of 10%, which is higher than the experimental results reported so far. Some of the simulation results are compared with those experimental results in the literature, and the accuracy of the model is well confirmed. These findings have important theoretical reference value and guiding significance for the design and development of thulium-doped fiber lasers.

In this paper, a full-rate linear 25 Gbps clock and data recovery circuit (CDRC) is proposed for the application of high-speed optical communication systems. To achieve full-rate clock extraction and data recovery, CDRC employed a mixer-based linear phase detector and automatic frequency locking technique. No external reference clock was used in the design. Based on a 45 nm CMOS process, the CDR circuit from the post-plate simulation results achieves that the peak-to-peak differential voltage Vpp and peak-to-peak jitter of the recovered 25 Gbps data eye diagram are 1.3 V and 2.93 ps, respectively. The output 25 GHz clock has a differential peak-to-peak voltage Vpp and peak-to-peak jitter of 1 V and 2.51 ps, respectively, with phase noise of -93.6 dBc/Hz@1 MHz. The chip has an area of 1.18×1.07 mm2 and consumes 51.36 mW at a supply voltage of 1 V.

In order to adapt to the development direction of high density and minization of the third generation infrared focal plane, a large array small pixel and low power consumption of 640×512-5 μm InGaAs shortwave infrared focal plane readout circuit was designed in this paper. The performance of the simple structure of 3T pixel unit was studied, and its influence on the chip dark current and focal plane noise was analyzed to realize the rolling curtain exposure operation mode, the dynamic operation of column level buffer and the four-channel output function. Programmable gain amplifier was used to achieve gain adjustment and noise suppression. Based on the standard CMOS technology of 0.18 μm 3.3 V, the performance analysis of the small pixel unit and the four-channel output of the array window and the linearity simulation were carried out at the input clock frequency of 5 MHz. The results show that the bias change of the input stage of CTIA is about 30 mV, the working frame frequency is 54 Hz, the output swing is 1.7 V, the maximum power consumption is less than 150 mW, and the linearity is 99.987%.

As a key component of laser scanning display system, it is an inevitable requirement for RGB combiner to be of miniaturization and high transmission efficiency applied in augmented reality. Waveguides formed by three different materials with high transparency in visible light band, such as silicon nitride, gallium nitride and SU8, were comparatively studied in aspects of refractive index difference, dispersion curve and single mode condition, as well as dimension, transmission efficiency and optical field distribution of multi-mode interference RGB waveguide combiners based on the waveguides. The results show that the performances of silicon nitride devices are somewhere between those of gallium nitride devices and SU8 devices. Gallium nitride devices have the largest core-cladding refractive index difference, the smallest single-mode cut-off size, and the shortest device length (2 000 μm). SU8 devices have the smallest core-cladding refractive index difference, the largest single-mode cutoff size, but the larger device length (3 600 μm) than that of gallium nitride devices. In addition, the average RGB transmission rate of the silicon nitride, gallium nitride and SU8 devices are 78%, 55% and 91%, respectively. The SU8 device dominates obviously. The optimized ultra-compact gallium nitride multi-mode interference RGB waveguide combiner is expected to be integrated to laser scanning monolithic systems, while SU8 multi-mode interference RGB waveguide combiner has great practical value in deformable systems due to its well flexibility. Those devices provide a solid technical foundation for the development of augmented reality systems towards microminiaturization and high transmission efficiency.

By designing a composite heat sink based on diamond micro-groove structure, the utilization of thermal conductivity difference changes the heat flux conduction, to optimize the problem of heat accumulation in the center of the VCSEL surface array due to uneven temperature distribution, thus improve the overall output power and reliability of the laser surface array. Based on the finite element analysis, a three-dimensional thermoelectric coupling model was established to study the effect of vertical-cavity surface-emitting laser surface array unit arrangement on the thermal crosstalk effect of the laser. Moreover, the effect of the change of microgroove shape and position in the diamond composite heat sink on the internal temperature of the semiconductor laser was also studied and analyzed. And the optimal structure was designed for further optimization of the laser output performance. The vertical-cavity surface-emitting laser facet array with diamond composite heat sink reduces the temperature difference of the laser emitting unit by 29% compared with the conventional diamond heat sink package structure. This provides a new idea for output power optimization of large-area semiconductor laser facet arrays.

In this paper, a tunable erbium-doped fiber random laser based on M-Z structure is proposed. The output process, the wavelength tunable output and the stability of random laser were experimentally studied. Two 2×2 optical fiber couplers were fused by optical fiber fusion to form an all-fiber M-Z filter structure. The experimental results show that the threshold power of the laser is 120 mW. The gain loss is changed by adjusting the tunable attenuator, and the wavelength tunable output is realized. The single-wavelength output is 1 554.4, 1555.2 and 1556.3 nm respectively, and the signal-to-noise ratio is 31.65 dB. The dual-wavelength output is 1 525.9, 1 556.2 and 1 531.6, 1 556.2 nm respectively, and the signal-to-noise ratio is better than 21.92 dB. The output of three wavelengths are 1 527.4, 1 546.9, 1 551.6 and 1 526.9, 1 530.0 and 1 549.8 nm respectively, and the signal-to-noise ratio is better than 20.10 dB. The four-wavelength output is 1 525.9, 1 530.1, 1 547.9 and 1 552.3 nm, and the signal-to-noise ratio is better than 18.95 dB. The stability of single wavelength and dual wavelength is better than 1.65 and 1.99 dB respectively. The slope efficiency of the laser is 0.627%. Therefore, the random laser can achieve single-wavelength, dual-wavelength, three-wavelength tunable output and four-wavelength stable output.

A scalable time jitter measurement module for SNSPDs was designed to address the diverse application requirements of superconducting nanowire single photon detectors (SNSPDs). Based on the analysis of the time jitter measurement principle of the SNSPD system, a digitization unit, a time-to-digital conversion (TDC) unit and a field-programmable gate array (FPGA) unit were designed to digitize the SNSPD output signal, measure the time information and read out the data. The resolution, linearity and time accuracy of the TDC unit of the module were calibrated. The test results show that the resolution of the TDC unit is better than 55 ps, the measurement data is linear and the time accuracy within 100 ns is less than 36 ps. By combining the practical SNSPD system, a time jitter characterization of about 100 ps is achieved. The feasibility of this module for time jitter measurements in SNSPD systems is verified by comparison with a commercial time-correlated single photon counting (TCSPC) module.

The factors of magnetron spurring affecting mixed-phase VOx thin film properties were examined: substrate temperature, oxygen-argon ratio, spurring time and working gas flow rate, by orthogonal experimental method (16 test-groups, 4 factors, 4 levels). Experiment was conducted and the temperature coefficient of resistance and square resistance values of the samples were recorded to analyze the trend of the electrical properties of the films with different levels of different factors. Then, combining mean and variance analysis and XPS analysis, the magnitude of the different factors affecting the electrical properties of the mix-phase VOx films was obtained in the following order: working gas flow＞substrate temperature＞oxygen-argon ratio＞deposition time. Finally, the optimal parameters for mixed-phase VOx films preparation were obtained: sputtering current 0.3 A, substrate temperature 270 ℃, oxygen-argon ratio 2.8%, deposition time 20 min, and working gas flow rate 120 cm3/min. The test results show that its TCR is -2.65%/K and sheet resistance is 1 102.1 kΩ/□.

A simple silicon microlens array manufacturing technology based on silicon micromachining technology compatible with MEMS process was developed in this paper. The photoresist hot melt method and plasma etching method were used to fabricate silicon microlens arrays of different sizes on silicon wafers. In the experiment, the hot melt technology and etching technology in the process of lens fabrication were studied deeply. Finally, the optimum technological parameters were determined, and the silicon microlens array with diameter of 20~90 μm and high surface quality was prepared.

A dwell time optimization method on particle swarm optimization algorithm is proposed for the high-precision magnetorheological machining of optical components based on pulse iteration principle. This method introduced the particle swarm optimization algorithm to optimize the residual error of the overall surface on the basis of the pulse iteration method. Through the determination of the overall dwell time, the optimal selection of each dwell time point was realized and the high-precision surface machining was achieved. The root mean square (RMS) and peak valley (PV) values of Φ156 mm optical surface simulation converged from the initial 169.164 and 1 161.69 nm to 23.492 5 and 807.215 6 nm. The simulation results show that the proposed algorithm not only ensures the accuracy of surface convergence, but also obtains stable and reliable dwell time distribution. The proposed algorithm is better than the common pulse iteration method, effectively reducing the mid-spatial error. This algorithm provides a solution for the dwell time calculation in the process of magnetorheological finishing optical components.

Microchannel plate (MCP) with ion barrier films is the core component in Low Light Level (LLL) Image Intensifier tubes in Generation Ⅲ. In this paper, the electron transmittance and ion blocking properties of IBFs were described. Monte-Carlo simulation method was used to calculate the electron transmittance and ion blocking ratio of BeO and Al2O3 under different conditions. The simulation results show that BeO IBFs has better electron transmittance than Al2O3 IBFs, while Al2O3 IBFs has better inferior ion blocking ability than BeO IBFs. It is proved that BeO is feasible as an ion barrier film.

As for the hook position deviation of nondestructive bond pulling test, the influence factors of the force of bonding wire was analyzed, and the influence of the hook position deviation on the state of the bonding wire was discussed. Further, a reliability verification scheme was proposed. Through experimental comparison, the results show that hook position deviation of the nondestructive bond pulling test has limited influence on bonding reliability.

A new type of fan-shaped cavity and trapezoidal rib microchannel heat sink is proposed. The performance of single cavity or rib and composite structures were compared by the univariate method in terms of velocity, pressure drop, and temperature. Based on enhanced heat transfer factor and entropy minimization method, the overall evaluation of micro radiators with different structures was carried out. The results show that the combined use of cavity and rib makes the boundary layer periodically interrupted and re-developed, and the combined heat dissipation effect of cavity and rib is better than that of a single rib or cavity structure. When Re is 1 300, the enhanced heat transfer factor is 1.535 4, much higher than 1.355 for a trapezoidal rib and 1.28 for a fan-shaped cavity. Entropy generation analysis shows that the combined structure has the least irreversible loss, which is consistent with the enhanced heat transfer factor.

The Ag electrodes were fabricated on the p-type gap surface, and the annealing environment was used to make good Ohmic contact at the contact interface between the metal and the semiconductor. The influence of different annealing environments on Ohmic contact surface was also investigated by characterization and comparison of scanning electron microscope (SEM), Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS). The results show that if the annealing time is too short, the area of atoms moving freely with energy is small, which is not conducive to improving the surface denseness of the sample. And if the annealing temperature is too high, the grains on the Ohmic contact surface are easy to merge, causing the roughness of the sample surface to increase. In addition, during the annealing process, the mutual diffusion, the formation of the compound and the alloy phase, and the oxidation reaction will also affect the Ohmic contact surface characteristics. Among them, the oxidation reaction is more intense than other reactions and has a greater effect than the contact resistivity. Therefore, a suitable annealing environment and effective control of the oxidation reaction are key to enhance the Ohmic contact performance.

The Siamese network-based trackers are limited by the inherent tracking mechanism and search area selection mechanism of the Siamese network tracking framework. When the object is under challenging scenarios such as occlusion, fast motion, and out-of-view, how to perform stable and obust object tracking is always an urgent problem for Siamese trackers. To this end, in this paper, an object-tracking algorithm that combines the Siamese region proposal network with the global optical flow (GOF-SiamRPN) is proposed. By assisting the motion trend information of the object with global optical flow, the proposed method could effectively solve the potential tracking issues in these challenging scenarios. Extensive experimental results on VOT2019 and UAV123 show that the proposed method achieves a performance gain of 2.0% and 1.8% compared with the baseline method. It also achieves a competing performance compared to other state-of-the-art trackers.

Road vanishing point detection is an important part of blind zone monitoring in advanced driver assistance systems. In view of the problems of low accuracy and large computation of existing vanishing point detection methods, a road vanishing point detection algorithm based on in-vehicle video images is proposed. The algorithm detected the image feature points based on Harris corner point detection by optimizing the score function to reduce the amount of operations in the tracking stage. It tracked the motion feature points by the pyramid optical flow method and frame difference distance, and accurately obtained the position of each feature point on the end frame. After removing the outlying points from the feature points, the K-Means clustering algorithm that optimized the initial clustering center was used to obtain the road vanishing point of the in-vehicle video image. Finally, the algorithm was applied to various vehicle driving scenes for testing. It can accurately detect the road vanishing points in the in-vehicle video images within a short running time, which proves that the algorithm is robust, simple and easy to implement.

The existing polar code soft-output decoders suffer from high resource consumption and low resource efficiency of the hardware implementation. In this paper, a Fast-RCSC decoding algorithm and its decoder hardware architecture were designed. The Fast-RCSC algorithm performed complete calculations on internal special nodes, reducing the decoding cycle while maintaining high decoding performance. Based on the similarity between different special node formulas, the resource consumption of special node modules was reduced by reusing calculation results of the introduced special node modules and reusing time-division multiplexing scheme of calculation modules. The storage resource consumption was reduced by sharing storage units and merging data with bit width lower than the limit. The synthesis results in CSMC 180 nm process show that the designed decoder has an area size of 2.92 mm2 and a resource efficiency of 245.2 Mbps/mm2 when the code length is 1 024 bits, which demonstrates different degrees of improvement compared to existing polar code soft-output decoders.

Aiming at the large field of view and lightweight requirement of solid imaging head-mounted night vision system, the optical system and mechanical assembly structure of binocular head-mounted night vision system were designed. Then, a high-strength carbon fiber epoxy was used for the shell material of the night vision system, and a new shell structure was optimized by Solid Works software. Finally, the thermal stability of the shell under extreme cold and high heat conditions was analyzed by finite element method. The simulation results show that the shell thermal stress of the night vision system is less than the yield strength of the material under the extreme conditions of -40 ℃ and 50 ℃. Moreover, the maximum strain has little effect on the imaging quality, display performance and mechanical structure of the optical system. The conclusion proves that the shell structure has good temperature resistance and reliability.

In order to solve the structural safety problem that may be brought by the long-term full load work of the miter gates of the ship lock in real time, an on-line deformation monitoring method of herringbone gate based on fiber Bragg grating (FBG) sensing technology is proposed. By modeling and simulating the structure of the miter gate, the stress distribution and the arch collapse of the gate body could be accurately understood. According to the force distribution, several fiber Bragg grating tilt sensors were arranged on the miter gate to dynamically monitor the tilt angle of every part of the gate body in real time. The dynamic change of inclination angle was transformed into structural deformation, and the mapping relationship between arch and deformation is established. The results show that the FBG tilt sensor has good repeatability and can accurately reflect the operation process of gate opening and closing. The maximum stress area of the monitored gate body is near the water seal of the bottom pivot of the gate. The maximum camber is less than 0.1° and the maximum deformation is less than 7 mm.

The optical vignetting effect exists in most optical imaging systems, which seriously affects the imaging quality. How to effectively improve the optical vignetting effect is the key point in the design of aerospace optical remote sensors. A radiometric calibration method was used to quantify the influence of the optical vignetting effect in the imaging system and to obtain the correction coefficients. The correction coefficients were optimized by polynomial fitting method, and the correction system was reduced by about three orders of magnitude after fitting, which greatly reduced the demand for storage resources of the embedded system. The polynomial fitting method effectively reduced the correction coefficients and improved the optical vignetting effect. The non-niformity error of the camera before correction is 13.2%, and after correction, the non-uniformity error is reduced to 3.8%, which meets the requirements of general imaging systems for response non-uniformity. The method is suitable for implementation in FPGA-based processors with fewer correction coefficients, high real-time performance and low resource consumption, and has practical engineering value.

Non-standard laying of power cables is the main cause of insulation failure, which affects the safe operation of cables. At present, the quality detection of cable laying mostly adopts manual contact measurement, which has strong subjectivity and low accuracy, and is easy to cause secondary damage to the laying area. In order to solve this problem, an automatic detection method of tunnel cable laying quality parameters based on point cloud is proposed. Firstly, the tunnel cable point cloud data was obtained at the cable laying construction position. After that, the cable point cloud was segmented based on the structural characteristics of the tunnel. Finally, the laying area was segmented from the cable point cloud based on color and morphological features, and the laying quality parameters were automatically measured. The average accuracy, recall rate and F1 score of the cable and laying area point cloud segmentation algorithm proposed in this study are all greater than 0.92, and the average absolute error of the four laying quality parameters measured automatically is less than 0.35 mm. Experiments show that this research method can accurately locate the cable laying area and automatically and accurately measure the laying quality parameters.

The mature three-phase flow phase holdup measurement sensor on the ground cannot adapt to the complex environment of high-temperature and high-pressure corrosion, and the existing downhole measuring equipment is complex. A fiber optic probe sensor was designed to solve the above problems. Sapphire was used as the front sensing material of the optical fiber probe. Due to the difference in refractive index of light between the gas phase and the liquid phase, the light intensity of the reflected light from the probe was detected to distinguish whether the optical fiber probe was in the gas phase or the liquid phase. By detecting the fluorescent light intensity coupled to the optical fiber through the optical fiber probe to distinguish the water phase or the oil phase, the measurement of the three-phase phase holdup of oil, water and gas in the oil well can be realized with a single probe sensor.

The remainder control is crucial to the development and manufacturing of aerospace products, and the remainders state recognition is an important part of it. The key which is to effectively extract local features in high noise pictures. However, existing methods have not been modeled well specifically for remainder scenes, and generic vision models are prone to overfitting the noise, making it difficult to filter the noisy signals effectively. To solve this problem, this paper proposes a learnable Filter Network, which replaces the heavy self-attention mechanism by a learnable filter which is used to learn spatial location interaction information. And then incorporates a mask for frequency domain component feature extraction to learn the emphasis information of different frequency bands. It is experimentally demonstrated that this method works better in remainder recognition scenarios, outperforms the convolution and self-attention models, and has better time complexity.

In order to realize the real-time and high-precision demodulation of microvibration signal, a method of laser Doppler microvibration detection and signal processing based on FPGA is proposed. The optical system with all-fiber structure was adopted, and the vibration signal processing system was designed with FPGA as the core. The phase unwrapping module was improved to enlarge the measuring range of vibration and make it suitable for simple harmonic vibration and complex vibration. The improved phase unwrapping module was verified by simulated vibration experiments. When the amplitude was less than 80 μm, the measurement accuracy was less than 5‰. Through the vibration measurement experiment of the actual vibration target of piezoelectric ceramics, the frequency measurement error was less than 1 Hz, and the measurement accuracy of amplitude and frequency was less than 1%. The experimental results show that the vibration signal processing scheme is effective in expanding the vibration measurement range and realizing high-precision target vibration demodulation.

The increase of photovoltaic capacity will lead to the small signal stability problem of the system. The generalized short circuit ratio index can be used to describe the small signal stability of the multi-photovoltaic feed-in system. Based on this, a maximum admission capacity optimization method for any node in the multi-photovoltaic feed-in AC network under the generalized short circuit ratio constraint is proposed. Firstly, the small signal stability analysis model of multi-photovoltaic feed-in system was established. Secondly, the generalized short circuit ratio was expressed in the form of unreduced extended impedance matrix. Considering the situation of any node in the photovoltaic access network, the maximum access capacity optimization model of photovoltaic based on generalized short circuit ratio constraint was established, and the improved particle swarm optimization algorithm was used to solve the model. Finally, the correctness of the method was verified by simulation.