Traditional MEMS electrostatic actuators have the problems of high actuation voltage and overshoot oscillation. The movable electrode oscillates continuously before stabilizing at the equilibrium position; hence, satisfying the comprehensive requirements of variable capacitors, optical switches, and other applications is difficult. To solve the above problems, this study adopts the design of a variable stiffness cantilever beam. With the characteristic of increasing stiffness with travel, the oscillation phenomenon is suppressed. The actuation voltage is effectively reduced, and the transient time is shortened. The simulation and experimental results show that when the stiffness of the cantilever beam increases from 5N/m to 35N/m, the transient time of the dynamic response decreases by 55.5% under the same voltage and 21% under the same travel, and the actuation voltage decreases by 23%.

Organic photodetectors have attracted considerable attention owing to the advantages they offer in terms of large-area processability, flexibility, adjustable spectral response range, low cost, and light weight. They play an active role in intelligent monitoring,communication, biomedicine, image sensors, and fluorescence microscopy. Organic photodetectors can be classified into broadband and narrowband based on their spectral response ranges. This paper introduces the basic structure, working principles, and key performance parameters of organic photomultiplier detectors in detail. Subsequently, the latest progress in broadband and narrowband organic photomultiplier detectors in the research field is summarized,expounding upon their practical applications. Finally, future development prospects of broadband and narrowband organic photomultiplier detectors are discussed.

An all-in-one design is presented for a polarization-insensitive metasurface with a centrally symmetric split-ring structure for generating various resonant modes. The types of resonant modes (LC, dipole, and higher order resonances) are identified and analyzed by investigating their spectroscopic properties theoretically and experimentally. Several higher-order resonant modes have significantly higher quality factors, Q (~230). These resonant modes are also highly sensitive to the dielectric properties of the surrounding material of the metasurface.Additionally, the EM properties of metasurfaces with asymmetric structures were also investigated. It was found that additional resonant modes at both 0.332 and 0.210THz could be excited and strengthened by increasing the asymmetry of the metasurface structure along the horizontal (x-axis) and vertical axes (y-axis).

SiC PCSS is a research hot spot in related fields. However, theoretical research on 4H-SiC PCSS in the literature is still based on lumped element models that can only provide qualitative results. A quantitative explanation of the experimental data under transient conditions in typical literature is still lacking. This study uses the device-circuit hybrid mode in Silvaco TCAD software to simulate the optical and electrical characteristics of the 4H-SiC PCSS combined with a self-written carrier mobility interface program. The simulated results of the single pulse response show that the variation in the peak photocurrent of the device with optical energy is in good agreement with the experimental data under transient conditions reported in the literature,indicating that the model and parameters used are reasonable. The study also calculates and analyzes the main factors that affect the single pulse response, including the pulse energy, pulse width, and silicon carbide thickness. The multi-pulse responses of the devices for the two 4H-SiC thicknesses are calculated and analyzed. The results and conclusions obtained in this study provide a good reference for further research on SiC PCSS

In this study, we investigated the effect of common point defects in silicon photocells on the response characteristics of devices under laser irradiation. We established a crystal cell model based on the first principles, compared the density of state values of silicon materials with Fe and Cu impurities, and analyzed the influence of common point defects on the response characteristics of silicon photocells. When the temperature of a photovoltaic cell changes after exposure to laser irradiation, its photoelectric response output characteristics alter owing to the sensitivity of a semiconductor material to temperature. Based on the principle of the lightgenerated electromotive force of a photovoltaic device, the response output model and onedimensional thermal conduction equation were used to calculate the vacancy and impurity response characteristics under 1064nm laser irradiation. The results showed that both vacancies and metal impurities could change the band structure and response characteristics of silicon materials. Under a laser irradiation wavelength of 1064nm, the irradiation time was 1μs, and power density was 4×105 W/cm2, where the gap atoms had the most dominant effects on the electronic structure and optical properties of the material. At this time, the absorption coefficient of the material was as high as 23952cm-1, and the quantum efficiency value was the largest,resulting in the strongest cell response and minimum output voltage.

This paper presents a correction algorithm based on line overscan data to solve the testing error produced by drifting image data in a full-frame transfer large-array chargecoupled device (CCD) and the noise introduced by the testing circuit, which prevent the accurate evaluation of the parameters of a CCD device. The effective image data and vertical overscan data were output simultaneously. The drifting image data were suppressed by subtracting the mean value of the vertical overscan data from the image data. In the testing circuit, the analog and digital modules simultaneously acted on a single line of the image data and vertical overscan data.The noise introduced by the testing circuit was eliminated by subtracting the mean value of the vertical overscan data from the image data. Experimental results showed that the proposed algorithm reduced the readout noise of the device by 20%. The ratio for values greater than 15eand 25e- in a dark difference image was reduced by 25%. The algorithm is suitable for a largearea-array CCD device and can correct the errors introduced by the testing circuit to improve the testing efficiency of a full-frame transfer large-area-array CCD device.件测试技术开发。

High-quality (high-Q ) on-chip microresonators have been shown to be a promising platform for Kerr soliton frequency comb generation. Si3N4 microresonators composed of multimode waveguides can achieve high-Q factors and anomalous dispersion, which are necessary for soliton generation. To further reduce the threshold power for generating a singlesoliton microcomb, a novel racetrack Si3N4 microresonator with Euler bends has been reported that achieves loaded Q factors greater than 5×106. Compared with conventional circular bends,the sudden change in the bending radius at the waveguide connection is significantly suppressed,which in turn suppresses mode interaction and reduces propagation loss. With this novel microresonator, single-soliton frequency combs with a repetition rate in the microwave Ka band and a bandwidth exceeding 20nm (corresponding to a pulse duration of 129fs) are generated using only a 47mW pump laser (33mW estimated on-chip pump power) under the auxiliary laser heating method

This study investigated the CMV4000 CMOS image sensor (CIS), which is widely used in the space domain. When designing the test circuit, the CIS radiation circuit board was separated from the FPGA data acquisition and transmission board, and the radiation circuit board and test circuit board communicated through a communication interface to realize radiation shielding protection of the FPGA data acquisition part during a radiation test. This prevented the FPGA data acquisition board from being affected by radiation. The power supply module, data acquisition, memory module, peripheral circuit, and the layout and wiring of the PCB were designed. The Verilog HDL hardware description language was used to drive the timing design of each function module to realize the CIS radiation-sensitive parameter test function. A 60Co γ ray radiation test of the CMV4000 CIS was used to analyze the degradation of radiation-sensitive parameters such as the mean dark signal, dark signal uniformity, and dark signal distribution versus total ionizing dose, and the reliability of the CIS radiation-sensitive parameter test system was verified.

The Monte Carlo simulation method was employed to investigate the influence of ionization effects resulting from high-energy electrons bombarding a semiconductor in electron bombardment complementary metal-oxide-semiconductor (EBCMOS) imaging devices on both the charge collection efficiency and gain of the electron multiplying layer. Further, a theoretical analysis was conducted to examine the effects of incident electron energy, doping concentration in the p-type substrate layer, thickness of the electron multiplying layer, and passivation layer on the charge collection efficiency and gain of the multiplying layer. The analysis revealed that increasing the incident electron energy (up to 4keV), reducing the thickness of both the electron multiplying and passivation layers, and lowering the doping concentration in the p-type substrate layer are all beneficial approaches to improve the charge collection efficiency and increase the multiplying layer gain to obtain high-gain EBCMOS devices

This article discusses the optical transmission performances of phase-change optical devices. A bending waveguide model covering Ge2Sb2Te2 (GST) thin films was established using the finite difference time domain method. The influences of the GST area,thickness, and position in the bending waveguide on the optical transmission efficiency and loss were obtained in both the crystalline and amorphous states. The results indicated that when the optimal coverage area of the GST was 0.415μm2, and the thickness was 17nm, the optical transmission of the device was not affected by the GST position. The maximum contrast of the optical transmission reached 90.8%, and the insertion loss was as low as 0.321dB. Broadband parallel transmission could be achieved in a wavelength range of 1500~1670nm. The device had a small size and high extinction ratio, which theoretically met the requirement for enhancing the accuracy of optical calculations. This study is significant in the development of non-volatile,parallel integrated photon matrix computing unit devices.

To examine the enhanced heat dissipation effect of a crossed-fin heat sink on a 100W LED stage spotlight and optimize the design, we analyzed the main geometric factors and mechanisms that affect the heat dissipation performance of the heat sink. To this end, numerical simulation and experimental verification were performed. The optimization objectives were set as the highest temperature of the LED chip and mass of the heat sink. A single-factor analysis was performed on the length and spacing of the short fins, followed by a dual-objective optimization using the NSGA-Ⅱ algorithm. Fuzzy C-means clustering was then applied to obtain different heat sink configurations for different application scenarios. The results indicate that the crossedfin heat sink effectively enhanced the heat dissipation performance by increasing the average convective heat transfer coefficient of the fin surface. Both the length and spacing of the short fins exhibited optimal values that influenced the heat dissipation performance per unit mass. With excessively long short fins or excessively small spacing, the convective heat transfer coefficient on the fin surface decreased. After dual-objective optimization, the crossed-fin heat sink reduced the highest temperature of the LED chip by 2.33℃ with almost no change in its mass

Thin-film transistors (TFTs) with a top-gate coplanar structure were fabricated using a free-gallium amorphous indium-aluminum-zinc-oxide film as the active layer and a polymethyl methacrylate film as the dielectric layer based on a low-cost solution process method,and the influence of the Al content in the active layer on the device performance was investigated.The results indicated that Al atoms acted as a carrier suppressor in the InZnO films. Therefore,the carrier concentration in the InZnO film decreased with increasing Al content and hence, the threshold voltage of the device moved forward positively, the off-state current of TFTs decreased, and the on/off current ratio of the device improved. Moreover, the hysteresis stability of the threshold voltage improved via the optimization of the trap density in the interface between the active and insulator layers by adjusting the Al content of the active layer. Overall, optimum device performance was achieved at an Al content of 30%.

This study explored the feasibility of employing metallic copper (Cu) as the cathode layer in tantalum electrolytic capacitors. The focus was on fabrication methods and performance testing of flat metal-insulator-metal (MIM) capacitors with a Ta/Ta2O5/Cu structure. An amorphous Ta2O5 thin film was deposited on Ta foil surfaces via anodization. Two Cu deposition techniques, namely chemical Cu plating and magnetron sputtering, were utilized to create the Ta/Ta2O5/Cu structures. These structures were subjected to extensive characterization and performance evaluation. The experimental results demonstrate the absence of capacitive characteristics in the Ta/Ta2O5/Cu structures fabricated via different Cu deposition methods during electrical performance testing, the resistance measured between the positive and negative electrodes was only 0.7Ω. And direct utilization of metallic Cu as the cathode layer in Ta capacitors leads to the oxidation of Cu into copper ions during the testing process,subsequently infiltrating the Ta2O5 dielectric layer and causing the breakdown of Ta2O5. Thus, it can be concluded that metallic Cu is unsuitable as a direct cathode layer in Ta capacitors

This study introduces an integrated approach for road crack detection that harnesses the strengths of both visual transformers and CNN. A CNN is employed to capture fine-grained details, and a visual transformer is fully utilized to capture global characteristics. A feature fusion module is then designed to seamlessly merge the extracted features from both methods, thereby addressing the limitations of using CNN or visual transformer methods separately. Finally, the results are fed into an interactive decoder to produce accurate road crack detection results. Experimental results demonstrate that, whether on a publicly available or selfconstructed dataset, the proposed method demonstrates an improvement in performance as compared with using CNN or visual transformer methods separately for road crack detection tasks

Endmember extraction is the key step in the mixed pixel decomposition of hyperspectral remote-sensing images. Traditional endmember extraction algorithms ignore the spatial correlation and nonlinear structure of hyperspectral images, which restricts their accuracy. To consider the spatial relationship and nonlinear structure of hyperspectral images, a nonlinear endmember extraction algorithm based on homogeneous region segmentation is proposed. A hyperspectral image was divided into several homogeneous regions using a superpixel segmentation method, and the manifold learning method was used to ensure the nonlinear structure of the hyperspectral images, extracting preferred endmembers within homogeneous regions. Simulation data and real hyperspectral image experiments showed that the algorithm proposed herein can guarantee the nonlinear structure of hyperspectral data, and the endmember extraction results were better than those of other traditional linear endmember extraction methods. Even in the case of a low signal-to-noise ratio, effective endmember extraction results were obtained.

Lasers, modulators, and photodetectors at the core of the microwave photonic link are active devices that introduce additional noise during the electro-optical-electrical conversion of microwave signals, deteriorating the noise performance of the microwave signals and thereby reducing the sensitivity, dynamic range, detection accuracy, and other key performance indicators of the electronic information system. Therefore, noise suppression has become critical to achieving high-performance microwave photonic systems. To overcome the limitations of current lasers with high noise, this study proposes the use of conventional distributed feedback lasers combined with optical amplifiers and narrow-band photonic filtering to suppress laser source noise and realize the broadband low-noise capabilities of the microwave photonic link. This study develops a microwave photonic link transmission model and analyzes the mapping relationship between the link performance and device parameters. The noise performances of the combined light source scheme and the conventional microwave photonic link are measured and compared, and the results show that the use of a high-power light source combined with optical filtering can achieve a high suppression of laser distal relative intensity noise (RIN). Through optimization, the noise figure can be improved by more than 15dB compared with the conventional level.

Objective The optical-domain Fourier transform provides a new solution for radio-frequency spectrum analysis. While this transform is limited by the acquisition of a large second-order dispersion, the discrete Fourier transform needs to control only the phase of discrete points, which can theoretically solve the problem of obtaining a large dispersion. Methods This study used a fiber optic ring as a discrete dispersion device and a linear frequency modulation signal as the test signal to study the optical-domain discrete Fourier transform. Each transformation in this fast Fourier transform system takes approximately 2.07ns. By observing the waveform delay of the linear frequency modulation signal before and after transformation using an oscilloscope, the transformation delay of the system (~100ns) can be measured. The feasibility of the on-chip integrated optical microring group scheme was examined to expand the instantaneous bandwidth of the system.

In this study, a two-stage peak detection circuit was designed to realize the peak detection and holding of a narrow pulse signal with a rising edge of 3ns, pulse width of 5ns,falling edge of 3ns, and re-frequency of 10kHz. The voltage-signal acquisition was accomplished using the analog-to-digital converter of an STM32 microcontroller. The basic structure of the ground detector with an APD as the photodetector is given in the block diagram, where the amplifier circuit module in the detector system is used to increase the width of the received laser pulse from 1ns to 5ns. The peak detection circuit module is used to detect and record the data of the narrow pulse. The signal source was used to complete a functional test of the peak detection circuit, and a laser with a heavy frequency of 1kHz and pulse width of approximately 1ns was used to test the whole detector system. The results verified that this system could better detect and record the peak of this laser signal.

A dual-frequency laser interferometer, as a commonly used precision optical noncontact measurement device, has the advantages of high precision, strong anti-interference ability, and good flexibility. However, factors such as ambient temperature changes and mechanical vibration may affect the accuracy of the measurement results, and the extent of this influence increases with the optical measurement path. To investigate a large-stroke displacement platform ranging system based on a dual-frequency laser interferometer, the measurement principle of a shifting platform ranging system was first studied. Next, the errors existing in the system were analyzed and compensated. Finally, a comprehensive error compensation experiment was carried out on the system, and the short-term compensation reached the order of 10-8 m, with a longer time producing a better compensation effect. The method was more complete than the existing error compensation method, and the compensation was larger.

To solve the spectral signal overlapping problem in fiber Bragg grating (FBG) sensing networks, this study proposes a spectral signal demodulation algorithm using a convolutional neural network model based on a field-programmable gate array (FPGA) and implements it in hardware for acceleration. The models parameters are quantized to a fixed-point representation, reducing the storage space of the model and enhancing the utilization of DSP resources in the FPGA. Hardware optimization techniques such as loop unrolling and array rearrangement are employed to improve real-time system performance, establishing a parallel computing scheme for the algorithm. The results indicate that under a clock frequency of 100 MHz, the demodulation accuracy of the test set is 1.19pm at an inference speed of 14.96μs per frame and a spectral demodulation rate of 60kHz. The proposed algorithm exhibits high precision and speed in the demodulation of overlapped FBG spectral signals.

The time-discrimination method determines the measurement accuracy of an entire system in the receiver circuit of a LiDAR (LightLaser Detection and Ranging). As the accuracy of the traditional leading-edge time discrimination method is not high and the constantratio timing method presents considerable device loss, a new time discrimination method is proposed. First, two voltage amplifiers with high and low gains are used in parallel to obtain two pulse-voltage signals with different gains. Subsequently, The front and back edges of the two pulse voltage signals are obtained using the four comparators. Finally, the centroid of the echo pulse is obtained using a geometric averaging algorithm, to determine the arrival time of the echo. MATLAB simulations showed that the accuracy of the proposed method is better than those of traditional methods. The output waveform of the voltage amplifier and comparator conformed to the expected results obtained by simulating the time-discrimination module by employing Multisim. Finally, the time application of the discrimination module designed by the proposed time discrimination method to the receiver revealed that the module satisfied the system accuracy requirements of the 3D imaging LiDAR receiver circuit in experiments, demonstrating a good 3D imaging effect

An average-minimum mean squared error (A-MMSE) channel estimation algorithm is proposed to address the problem of a high bit error ratio (BER) of the minimum mean squared error (MMSE) channel estimation algorithm in orthogonal frequency division multiplexing (OFDM) systems. The proposed algorithm first constructs a new pilot structure based on the 802.11n standard. Then, downsampling and oversampling processes are performed at the receiver and transmitter, respectively. Finally, the channel frequency response is obtained using the known training sequences and pilots. The simulation results indicate that, compared with the traditional MMSE algorithm, the proposed A-MMSE channel estimation algorithm improves the signal-to-noise ratio by approximately 8dB at a BER of 10-3. Therefore, the proposed channel estimation algorithm notably improves the BER performance of the system.

A method for estimating the indoor height of pedestrians based on micro pressure sensors was developed to address the issues of errors accumulated over time in the height calculations performed using the current pressure sensors. In this method, based on the output height value of a micro pressure sensor, an algorithm judges the height values of multiple adjacent time points. It constrains the height change based on the indoor pedestrian movement status such that this change conforms to the indoor pedestrian movement law. Simulations were performed using data from a MS6511 micro pressure sensor. Experimental results indicate that the proposed method effectively corrected height errors. As compared with the height errors calculated using micro pressure sensor data, the trajectories calculated with the proposed method were closer to the real ones. The average closed-loop error decreased from 1.9%D to 0.07%D, effectively improving the positioning accuracy of indoor pedestrian height estimation. This method has engineering application value in the field of indoor 3D pedestrian positioning.

The Phase Generated Carrier (PGC) demodulation algorithm is currently an important demodulation algorithm in the field of fiber optic interferometric sensing. To overcome the problem of light intensity perturbation and modulation depth affecting the accuracy of signal demodulation in the current PGC demodulation algorithm, an improved PGC demodulation algorithm (PGC-Ameliorated) is proposed, and a vibration sensing system based on Distributed Feedback (DFB) lasers is built for experimental verification. The experimental results show that when the frequency of the measured vibration signal is 800Hz, the signal-to-noise ratio of the algorithm is 57dB; this is better than those of the Differential and Cross Multiplying (DCM) and Arctan algorithms. At different values of light intensity, the amplitude of the demodulated signal fluctuates in the range of ±0.02rad. At different values of modulation depth, the algorithm exhibits a minimum total harmonic distortion of 0.61% and a maximum signal-to-noise ratio of 25.9dB that provides lower total harmonic distortion and higher signal-to-noise ratio than the DCM and Arctan algorithms.

To address the problems of low localization accuracy and map vignetting in Visual Simultaneous Localization and Mapping (VSLAM) technology in dynamic environments,this paper proposes a dynamic SLAM algorithm based on deep learning. The proposed algorithm utilizes YOLOv8n, which has few network parameters and a high target recognition rate, to improve the visual front end of the system, add semantic information to the visual front end, and extract the dynamic region feature points. The LK optical flow method is then used to identify the dynamic feature points in the dynamic region, eliminate these dynamic feature points, and retain the static feature points in the dynamic region so as to improve the utilization rate of feature points. In addition, the proposed algorithm increases the map construction thread,eliminates the dynamic object point cloud extracted by YOLOv8n, receives the semantic information extracted by the front end, constructs a static semantic map, and eliminates the virtual shadow produced by dynamic objects. Experimental verification indicates that the proposed algorithm improves the localization accuracy in dynamic environments by 92.71% as compared to that of ORB-SLAM3. Further, it achieves a small improvement compared with other dynamic vision SLAM algorithms.

To address the problems of high noise and low signal-to-noise ratio in singleended Brillouin optical time-domain analysis systems, a denoising method based on empirical mode decomposition (EMD) was developed. Theoretical analyses of the denoising principle of EMD and the sensing principle of single-ended Brillouin optical time-domain analysis in a fewmode optical fiber were conducted. The denoising effect of EMD was comparatively analyzed by constructing a single-ended Brillouin optical time-domain analysis temperature-sensing system.The experimental and simulation results show that the EMD algorithm exhibited a good denoising effect on the temperature sensing system and that it improved the signal-to-noise ratio and temperature measurement accuracy by approximately 3.06dB and 0.98℃, respectively.