This PDF file contains the front matter associated with SPIE Proceedings Volume 12959, including the Title Page, Copyright information, Table of Contents, and Conference Committee information.

The high-power picosecond laser systems have been used in many fields, such as materials dynamics research, cancer treatment, and high spatial and temporal resolution backlight radiography[1] . Compared to nanosecond laser, picosecond laser with higher peak intensity can generate more serious fast nonlinear growth, which leads to the small-scale autofocusing (SSSF) effect and the beam splitting into filament, affecting the safe operation of the laser system and limiting its output capability. How to effectively suppress the fast nonlinear growth and improve the near-field quality of the output beam in picosecond laser systems has become a hot topic of interest. In recent years, a band-stop filtering technology based on volume Bragg gratings (VBGs) has been proposed, which can effectively filter out the specific medium-high frequencies (MHFs) of the beam and suppress the SSSF effect. In this paper, a filter based on the composition of two VBGs is designed to take advantage of the excellent angular selectivity of the VBG. The incident angle of the incident beam is matched with the first diffraction zero point of VBGs to constitute a band-stop angular filter (BSF). Combined with the picosecond laser amplification system, the ability of BSF to suppress the fast nonlinear growth generated is investigated. The near-field distribution of the beam through is numerically simulated. This method proposed in this paper effectively suppresses the SSSF effect of the beam in high-power laser systems and provides a new technical approach for picosecond laser amplification.

Laser beam figuring (LBF), as a processing technology for ultra-precision figuring, is expected to be a key technology for further improving optics performance. Due to the lack of understanding of the multi-physics coupling between laser and fused silica, there is still no existing mechanism to guide nano-precision form correction, which severely restricts its further development. To acquire nanoscale high-precision figuring, accurate control of figuring depth is needed. In this paper, we found that fused silica experienced the densification process, leading to nanoscale volume shrinkage subsidence. Therefore, a mathematical model is established to reveal the mechanism of densification effect on nanoprecision figuring depth. The figuring depth of fused silica irradiated by CO₂ laser is related to heat-affected zone and fictive temperature. The results indicated that the figuring depth exponentially depends on pulse duration and figuring depth levels of nanometer are obtainable with the control of pulse duration. The simulation results of CO₂ LBF were finally compared with the experiment ones, which verified the feasibility of the established model. These studies could provide guidance for the optimization of parameter selection and the improvement of LBF technology.

In order to further improve the accuracy of quantitative analysis of coal quality by laser induced breakdown spectroscopy (LIBS), the influence of data set partitioning method on quantitative model was studied. The spectral data of 40 different coal samples were collected, and the Support Vector Regression (SVR) model and random forest (RF) model were established by Random Selection (RS), Kennard-Stone (KS) and Sample Partitioning based on joint X-Y distances (SPXY), respectively. The prediction results of ash, volatile matter and calorific value under the two models were compared. The results show that the regression model established by SPXY method combined with RF algorithm has better fitting prediction performance. The predicted root mean square errors (RMSEP) of ash, volatile matter and calorific value are 1.8872, 1.4537 and 0.9020, respectively, and the mean relative errors (MRE) are 6.96%, 3.87% and 2.14%, respectively.

In the compact atomic gyroscopes, the vertical-cavity surface-emitting laser (VCSEL) is usually utilized as the laser source. However, the power of VCSEL is not sufficient to polarize the nuclear spin efficiently. To solve this problem, we put forward a multi-laser module design for optical pumping in compact atomic gyroscopes. In this module, several lasers are integrated in one module and utilized together for pumping. We fabricated and tested a laser module with two VCSELs for demonstration. First of all, the beam collimation system is simulated, and it is concluded that the two lasers can be integrated on the same micro-heater and collimated by the same lens. This is proved experimentally by beam profile measurement. Furthermore, the polarization distribution is simulated and investigated, and the results indicate that the polarization and its homogeneity can be increased significantly when pumping with two lasers. Finally, the nuclear polarization is measured experimentally, and it is demonstrated that the nuclear polarization when pumping with two 1 mW lasers is increased from 3.71% to 5.52%, and the proportion of the increase is more than 48% compared to that when pumping with a single 1 mW laser. These results prove the feasibility of the design, and this multi-laser pumped regime provides new inspirations for the development of compact atomic gyroscopes.

Dual wavelength lasers have wide applications in optical communication equipment, lidar, and other fields. The measurement and control of dual wavelength laser power ratio affect the application value of dual wavelength lasers in these fields directly. The dual wavelength dye laser used in the experiment has a wavelength difference of only several picometers. Based on this demand, our paper innovatively proposes a measurement method that using a scanning FP interferometer to characterize the power ratio. The linear correlation between spectral response and incident light power was verified through the establishment of theoretical models and experimental verification. On this basis, the optimization of optical layout design and the design of automatic recognition software can be carried out separately to achieve online monitoring of power ratio. Finally, the device was used for long-term experimental assessment, and the results showed that the comprehensive error of dual wavelength power ratio measurement based on scanning FP interferometer was less than ± 3%, which met the experimental requirements.

Triple-junction GaAs solar cell having high photovoltaic conversion efficiency and high irradiation resistance, can be used as a basic unit of photovoltaic module in laser power supply system. Due to excessive laser energy, solar cell will suffer irreversible damage. For meeting needs of laser power supply and anti-laser protection of solar cell, a thermal effect calculation model of triple-junction GaAs solar cell under laser irradiation is researched and established, which is based on solar cell’ simplified structural model. Simulation analysis of solar cell’s thermal damage is carried out, considering some factors, such as laser power density, reflectivity and initial temperature. Simulation results show that power density that solar cell can bear is less than 1.8 W/cm2 under the long-time irradiation of 1070nm continuous laser. The anti-laser damage capacity of solar cell can be significantly improved by use of laser protection cover-glass, which can improve solar cell’s reflectance from 0.08 to 0.6. After that, power density that solar cell can bear is less than 4 W/cm2 under the long-time irradiation, or even 7 W/cm2 under 30 seconds irradiation. The effect of initial temperature can be equivalent to irradiation time difference. But it can be ignored under long-time irradiation of laser.

With the rapid development of laser technology, the potential risk of on orbit satellites being attacked by laser becomes more and more prominent. According to the types of exposed parts of the satellite, the degree of damage and the impact on the satellite function, the vulnerability analysis of the satellite system to laser irradiation was carried out. The results show that the satellite solar array, thermal control components, star sensors and communication antennas are vulnerable to laser attack, and have different degrees of impact on the long-term or short-term operation status of the satellite. Based on the general function module and information logic of the satellite, the satellite laser irradiation threat assessment software is constructed, and the quantitative assessment results of the damage of different components affecting the satellite status under typical space conditions are obtained through settlement, so as to carry out risk assessment and provide reference for formulating defense strategies.

Triple-junction GaAs solar cells were irradiated by nanosecond pulse laser with a wavelength of 1064nm, in atmospheric and vacuum environments respectively to study the damage characteristics of triple-junction GaAs solar cells irradiated nanosecond pulse laser in different environments, and the damage effects of pulse laser in two environments were compared and analyzed. The experimental results show that the damage of solar cells irradiated by nanosecond pulse laser is significantly affected by the target energy density, and the damage effect is positively correlated with the number of pulses, which increases with the number of pulses. Due to the high peak power, short action time, no obvious thermal effect of the action process, and no material migration phenomenon, the damage effect of solar cells is similar under pulsed laser irradiation with the same parameters in different environments.

Ultrafast electron diffraction using photocathode microwave electron guns is a powerful tool for investigating ultrafast science. To improve the spatial and temporal resolution of diffraction, it is crucial to enhance the quality of the electron beam, particularly the initial quality of the electron beam emitted from the photocathode that is influenced by the driving laser. To meet the strict requirements, the performance parameters of the femtosecond laser transmission system play a significant role. In this paper, we analyze the impact of femtosecond laser system parameters on diffraction resolution and investigate the primary indicators of the femtosecond laser system. We conducted experiments to measure the primary parameters of the laser, including pointing stability, beam diameter, pulse width, and pulse energy. Based on the experimental results and considering the complexity of engineering implementation, we proposed an optical scheme for the femtosecond laser transmission path to satisfy the requirements of the ultrafast electron diffraction device for further improving the diffraction resolution. This research aims to provide valuable insights into optimizing the femtosecond laser system for ultrafast electron diffraction experiments.

Tapered semiconductor lasers are widely used in space communication due to their high output power and high beam quality. The tapered semiconductor laser structure mainly consists of ridge region, absorption region and tapered region. The tapered semiconductor laser is analyzed by characterization methods such as EMMI, EDS and FIB-SEM in this paper. It is found that the waveguide damage in the ridge region is caused by the enhancement of the local optical power density in the ridge waveguide, and there are failure points inside the waveguide and the sidewall of the device, resulting in photon leakage. The closer to the optical cavity surface, the more holes between the solder and the electrodes, and the presence of oxygen elements near the optical cavity surface, indicating that the interface holes existing in the optical cavity surface would lead to the migration of oxygen elements. The research results reveal that the enhancement of local power density in the ridge waveguide is caused by the optical feedback process. The main failure mechanisms of the device contain the solder holes and the enhancement of local power density, which provide an important reference for the process optimization of high-power tapered semiconductor lasers.

Aiming at the problem that the laser coherent detection system is easy to be annihilated in the noise in the long-distance and complex environment, resulting in the system unable to extract effective information, In this paper, the pulse compression theory and matched filter principle are analyzed, and a target high-precision matched filter LFM system model suitable for laser coherent detection is proposed, by transmitting a linear frequency modulation signal, combined with the matched filter algorithm to process the echo signal, realizes the target distance solution under the condition of low signal-to-noise ratio. At the same time, the influence of FM bandwidth on the multi-target extractionability under different SNR is studied, and the FM bandwidth-ranging accuracy model is established. Compared with the ordinary windowing algorithm, by increasing the system FM bandwidth, it can be effective in extremely low signal-to-noise ratios. Extract multi-target distance values. The simulation results show that under the condition of -40 dB signal-to-noise ratio, setting the frequency modulation bandwidth to 4 GHz can effectively achieve multi-target detection, and the ranging accuracy can reach 4.5 mm.

Full-waveform hyperspectral light detection and ranging (FWHSL) is vital in retrieving spatial and spectral information during laser scanning. Four main influence factors, the distance between two neighbor targets, the coverage ratio, the incident angle, and the target's reflectance, determine the information of the FWHSL returns. Previous studies mainly focus on the influence of the neighbor distance, incident angle, and reflectance, while we focus on the coverage ratio of the targets in a laser footprint. We propose a novel multispectral waveform decomposition method, including the Trust-Region algorithm for single wavelength waveform decomposition, 3σ rule for screening decomposition results and correction between multispectral waveform decomposition, to obtain the accurate spatial and spectral information from the multispectral returns, which realizes the decomposition error less than 0.3cm when the neighbor distance is 40cm, for a 4ns pulse width LiDAR signal. We find the intensity and overlapped ratio of the returns are strongly related to the coverage ratio, which may accelerate the progress in point cloud information extraction and target recognition.

Aiming at the problems of high cost and large size of the traditional mechanical lidar scanning point cloud, a point cloud data acquisition hardware system and a single-site cloud registration procedure were developed by using the prismatic lidar with low cost, small size and petal-shaped point cloud. Since the density of the point cloud collected by this lidar is time-dependent, in order to obtain a high-density point cloud, each station adopts a data collection method in which the motor-controlled lidar rotates 22.5 degrees each time, rotates 16 times, and scans the environment for one week. Using the self-developed station data processing programme, the data from each station were aligned according to the angle of the data by rotating the data through the space vector rotation algorithm. In the stage of inter-station point cloud registration, the original feature constraints of the multi-site cloud are obtained, and the error equations are derived from the constraints through the initial solution of all the station transformation parameters and unknown points except the control points. The weight function established by each constraint error is used as the constraint for iterative settlement until the iteration conditions are met, and all site space transformation parameters and location coordinates are output to achieve overall registration of multi-site cloud. This experiment shows that the point cloud data collected by the self-developed low-cost lidar has high density, high resolution, and the accuracy after registration is about 2cmin the nominal accuracy of prism lidar hardware, which has strong practicability and feasibility.

To ensure the proper operation of the Nuclear Magnetic Resonance Gyroscope (NMRG), a dedicated amplitude control circuit has been designed for the gas chamber. This circuit aims to fulfill the high-temperature heating requirements of the gas chamber, including achieving saturated vapor pressure, higher density, and ensuring the precise temperature stability of the gas chamber. The stability is of utmost importance as it directly impacts the accuracy of the NMRG. The circuit employs a voltage-output DAC1220, connected in series with a resistor, to drive the FS ADJUST pin of the AD9834. This configuration allows precise adjustment of the amplitude of the full-scale DAC current. The resulting signal is then amplified using a current-to-voltage conversion resistor and an Enhanced Howland Current Source (EHCS) circuit, effectively meeting the requirements for heating the gas chamber. The simulation and experiment show that the successful achievement of an AC sinusoidal heating signal with a frequency of 100KHz and a precise amplitude adjustment rangeof0-150mA.The adjustable step size of 0.01v ensures fine-tuned control. These findings validate that the heating signal fulfills the requirements for high-frequency electrical heating of the gas chamber in the NMRG.

We design a laser driver and temperature control circuit based on the Field Programmable Gate Array (FPGA). Vertical-Cavity Surface-Emitting Laser (VCSEL) is the core device of the nuclear magnetic resonance gyroscope (NMRG). The accuracy of the laser output wavelength greatly affect the detection accuracy of NMRG. In order to improve the accuracy of VCSEL in this application system, in this paper we research the working principle of the laser and analyze the relationship between the laser output wavelength, the driving current and the laser operating temperature through theoretical analysis. We design and built the laser driving and temperature control circuit by using constant current source and the MAX1978, which use FPGA as the main control chip. By setting different voltage values, the laser output corresponds to different wavelengths. We analyze the result of experiment and theoretical calculate through the spectrometer. The result shows that the current regulation error is better than 0.03mA. For the laser temperature control circuit, we used the LTSPICE to simulate the PID control circuit of the compensation loop ,the finally result is consistent with the expected results.

This study establishes a laser propulsion system with a pulsed laser at the tip of a tapered optical fiber, and investigates the interaction between polystyrene (PS) microspheres and nanosecond laser pulses in water. The system can effectively control the generation of laser energy and spot, achieving precise microsphere propulsion. Additionally, we employ a laser propulsion system with a conical fiber structure to separate and remove PS microsphere clusters in water. This type of laser propulsion system is characterized by simple operation and precise positioning, and based on these features, the study of PS microsphere propulsion using the conical fiber laser propulsion system holds potential applications in underwater laser cleaning and underwater microstructure manipulation.

The laser irradiation effect of three-junction GaAs solar cell arrays was studied through the experiment of fiber laser irradiation under different irradiation time and power density. The photocurrent voltage characteristics of solar array before and after laser irradiation were tested, The dark current voltage characteristics and spectral response of each solar cell array after irradiation were tested. The test and analysis results reveal that, The radiation damage of continuous laser to the array, due to the uneven energy distribution of the laser spot, the damage degree at different positions of the array is different. The damage of a single battery varies greatly, ranging from slight damage to complete failure. In the area with medium or strong laser power, continuous laser first damages the first and second junctions corresponding to the top cell and the middle cell, while the third junction corresponding to the bottom cell has less influence; In the area with weak laser power, the damage to the battery interior caused by continuous laser starts from the bottom battery with the smallest band gap, followed by the top battery and the middle battery.

Bound soliton (BS) states, as an interesting physical phenomenon operating at multi-pulse mode, are intensively investigated both theoretically and experimentally. However, the BSs have rarely reported in bidirectional fiber ring lasers. Here, we demonstrated a bidirectional passively mode-locked all-fiber ring laser with BSs output at 1.55 μm. The laser is mode-locked by a single-wall carbon nanotube absorber. Two synchronous single-soliton pulses in clockwise and counter-clockwise directions were delivered simultaneously from the laser, which could be transferred to the two-soliton bound states. The bidirectional operations showed the same BS states with phase differences of -π∕2, 0, and π.

Laser measurement system has the advantages of fast speed, high precision, and cost-effective. But the laser itself coherently produces speckles, the presence of laser speckle can seriously degrade image quality, leading to decrease in image recognition accuracy, thus reducing the accuracy of measurement. In this paper, we propose a multi-beam superposition method to reduce laser speckle. We use four lasers with equal optical power as the incident light source, then build the entire system light path by beam shaping and polarized beams superimposing, which achieves the line structured light required for the laser measurement system. According to the theoretical analysis and simulation optimization, the speckle contrast was reduced to 50% of the original value in this way. After beam shaping, we can obtain the linear laser beam with a line width of less than 1mm, a field of view angle of 66.8°, a light energy loss of less than 10% and an energy uniformity of 97.25% at a projection distance of 1000mm.The above results highlight a viable approach to decrease speckle contrast and measurement errors. This system can achieve high power and low speckle contrast light sources in the field of measurement, with outstanding result in practicability and convenience. On the other hand, this system can effectively solve the problems of serious error and low efficiency in measurement.

Significance: The production and characteristics of protonated small water clusters (PSWCs) were reported in this work, where in electrospray ionization (ESI) of pure water, the species obtained were singly charged molecular ions consisting of 2, 3, 4 or 5 water molecules attached to a hydrogen ion, [(H2O)n+H]+ , where n = 2, 3, 4 or 5. We proposed a new type of PSWCs structure: 2, 3, 4, 5 water molecules wrapped around a hydrogen ion which is located at the electrical and geometric center, forming a very stable molecular structure. Furthermore, biological tests of the PSWCs on mitochondrial function of intestinal epithelial cells and liver cells in mice showed the better therapeutic effect on inflammatory bowel diseases compared to that of the biologic agent Infliximab. Aim: To produce stable PSWCs as a new source of nutrient for health. Approach: The PSWCs were produced by electrospray technology, and identified by an electrospray mass spectrometer. The biological effects of the PSWCs on mitochondrial function of intestinal epithelial cells and liver cells in mice are carefully checked. Results: The production, characteristics and the biological effects of the PSWCs are studied, that we first generate the PSWCs by electrospray mechanism, which is proved to be charged (with positive charge). The obtained PSWCs are composed of 2, 3, 4, 5 water molecules plus a proton, respectively. The test of biological effects shows that the PSWCs can reduce radicals and improve the cell functions, indicating very important biological functions of the PSWCs. Conclusions: PSWCs was successfully produced by electrospray technology in our lab, the produced PSWCs were very stable under normal conditions without any obvious concentration changes of hydrogen ions in the last 3 years after produced, even the water is heated to 100 degrees Celsius. Furthermore, the effect of PSWCs on mitochondrial function of intestinal epithelial cells and liver cells in mice showed that the therapeutic effect of PSWCs on inflammatory bowel disease was better than that of the biologic agent Infliximab, where the higher the concentration of hydrogen ions, the better the therapeutic effect is.

Recently, 2D layered MnBi₂Te₄ has been a promising candidate for discovering the exotic topological quantum phenomena for the coexisting topology and magnetism. In particular, the layered structure of MnBi₂Te₄ with a small bandgap possesses excellent ultrafast nonlinear response and broadband saturable absorption, which indicates that they can be applied in the field of ultrafast photonics. Despite tremendous research on magnetism and topology, the nonlinear optical properties of MnBi₂Te₄ have been underexplored. Herein, we have successfully synthesized the high-quality MnBi₂Te₄ by the self-flux method. By using MnBi₂Te₄ nanosheets as a saturable absorber (SA), a passive mode-locking erbium-doped fiber (EDF) laser centered at 1560 nm was obtained with a pulse duration of 331 fs. This work suggests that magnetic topological insulators possess great potential for ultrafast photonics.

The article proposes a measurement method using the sparse distribution detector array, and it can accurately measure the key terminal ballistic parameters (including hitting coordinates, flight velocity, firing angle and firing rate, etc.) of the supersonic projectile. Firstly, we describe the shock wave of the supersonic projectile and its propagation characteristics. What is more, the detection principle of the system is presented. Secondly, its measurement model is established through combining with the relevant structural parameters and the shock wave propagation velocity in the detection area. Next, the system is developed, and it mainly consists of several pairs of laser emitters and their receivers, two support frames, and a signal conditioning circuit. Finally, the systematic errors of the above parameters are analyzed through numerical simulation, respectively. The results show that the measurement method can meet the requirements for testing the terminal ballistic parameters of the supersonic projectile. Compared with the previous methods, it has the advantages such as better uniformity detection sensitivity, high accuracy, lower cost, easy installation and adjustment.

Drag balloon deorbit device faces problems such as low packaging density and membrane damage during folding, as well as oscillations caused by inappropriate mass rates. In this study, aimed at improving the folding efficiency of drag balloons and ensuring smooth deployment, we propose a new folding method that combines flat spiral bonding with Z-folding. LSDYNA is used to establish a simulation model, and the deployment process of this folding model is analyzed using the Corpuscular Method (CPM). Specifically, we explore the necessary conditions for the smooth inflation and deployment of a drag balloon from the perspectives of the number of valves and mass rate. The results demonstrate that the proposed folding method is a low-damage, high-density one. Increasing the number of valves reduces the oscillation amplitude during the deployment process, enabling the drag balloon to reach a stable state earlier. Increasing the mass rate accelerates the oscillation frequency during the deployment process, which in turn requires more time for the drag balloon to regain stability. Therefore, to ensure the smooth deployment of the drag balloon during inflation, methods such as increasing the number of valves and reducing the mass rate can be employed.

As an emerging space industry, it is necessary to consider whether there are economic feasibility and endogenous power to achieve sustainable development. Based on the analysis of the characteristics of existing commercial on-orbit servicing (OOS) projects and OOS application scenarios, the market scale of OOS and the economic value of typical services are analyzed by using industry data and net present value method. Furthermore, value drives of OOS are analyzed and multiple OOS business models are put forward from the perspective of enterprise value creation and transmission, with their applicable situations, implementation methods and application scenarios defined. Finally, suggestions on the development of OOS industrialization are carried out from the aspect of industry ecosystem construction. The results show that on orbit services in GEO area is large-scale and economically feasible, and flexibility is the core value driving factor of OOS; the key to sustainable development of OOS industry is to incorporate the flexibility elements of maintainability and OOS capability into solutions for future space systems. The results could provide guidance and reference significance for the development of the OOS industry and for relevant markets entities to formulate domestic and foreign market development strategies.

This paper uses an ultrafast laser with a wavelength of 532nm and a pulse width of 10ps to conduct cutting process experiments on typical grades of CFRP materials in the aerospace manufacturing field, such as high-modulus CFRP and high-strength CFRP. After optimizing laser parameters and processing paths, a high-quality processing effect with minimal heat affected zone was obtained, and the fracture morphology characteristics and mechanical properties of the processed specimens were studied. The results indicate that under the laser wavelength, pulse width, and processing parameters selected in this paper, the morphology of the cut edge of typical CFRP materials was observed without visible heat affected zone through 200x optical microscope magnification, and the processed section was bright and burr-free, the fiber bundle section was neat, and the resin section was smooth through 2000x scanning electron microscope observation. Through the mechanical tensile testing, compared the ultrafast laser processed tensile specimens with the traditional mechanical cutting and punching tensile specimens, the ultrafast laser processed specimens of many typical grades of CFRP materials all have higher tensile mechanical properties, which also proves that the ultrafast laser pulse width and wave band used for CFRP materials have excellent processing quality, and are suitable for promotion and application in the aerospace manufacturing field. Finally, this paper introduces the typical applications of ultrafast laser processing CFRP in aerospace products.

Cylindrical vector beams(CVBs) are spatially non-uniform polarization distributions. It has been widely used in microscopic imaging, particle manipulation, beam shaping, and other fields. Accurate measurement of the CVBs polarization state distribution is one of the research problems. In order to analyze the influence of systematic errors on the CVBs polarization parameters, the measurement errors of the polarization azimuthal AOP under annular sampling are investigated in this paper. Firstly, the generation of CVBs and the measurement principle of Stokes parametric method is introduced; secondly, the radial and angular vector beam intensity images and the AOP distribution under different annular sampling are simulated; then, the variation of R=256 intensity error IΔ with the polarization azimuth error θ in the range of [-2°,2°] is analyzed. Finally, the single error and the coupling error are analyzed and discussed. The simulation results show that the intensity errors I_Δ1 and I_Δ2 are the same with the θ, and IΔ3 and IΔ4 are the same with the θ. Under the single error, the absolute error values of the AOPs with mutual residual angles are similar. The maximum absolute error of AOP of I_Δ1 and I_Δ2 is 1° (@45°) and the maximum relative error is 2.59% (@30°); the maximum absolute error of AOP of I_Δ3 and I_Δ4 is 1°(@0°) and the maximum relative error is 5.12% (@15°). Under the coupling error, the absolute AOP error of I_Δ1 and I_Δ2 increases with the increase θ, with the maximum value of 2° (@45°) and the maximum relative error of 5.25% (@30°); the absolute AOP error of I_Δ3 and I_Δ4 decreases with the increase of θ, with the maximum value of 2°(@0°), with a relative maximum error of 10.40% (@15°). The study provides an error data reference for CVBs polarization detection. It can provide technical support for the application of CVBs in different fields.

The accuracy and reliability of train positioning are crucial for ensuring safe train operation. Currently, inertial navigation systems are widely used in various autonomous navigation fields. However, inertial navigation suffers from the problem of error divergence over time. Therefore, to compensate for the drawbacks of inertial navigation systems, combined navigation has become a development trend in inertial navigation technology. Combined navigation using inertial navigation and laser velocimetry is a high-precision positioning solution. However, it still faces the challenge of error accumulation. Considering the requirements of real-time performance, high precision, and immunity to external environmental interference in train positioning, this paper introduces geomagnetic navigation into the combination of inertial navigation and laser velocimetry. This approach aims to solve the problem of error accumulation and further improve the accuracy of combined navigation. The proposed method is validated through onboard combined navigation experiments.

A 1319 nm single frequency nanosecond pulsed laser based on injection seeded is demonstrated. The laser oscillator is injection seeded by a 1319 nm single-frequency narrow linewidth Nd:YAG nonplanar ring oscillator (NPRO), a laser pulse of repetition rate of 500 Hz, pulse energy of 2.3 mJ, pulse width of 70 ns, and jitter of <3 ns is obtained based on ramp-hold-fire resonance detection technology. Then, through a four-stage end pump laser amplifier, the pulse energy is amplified to 15.4 mJ, with a beam quality factor of M²<1.5.

Laser active detection is a remote sensing technology that utilizes laser beams to detect various attributes of a target such as distance, orientation, height, and speed. The direct detection Signal-to-Noise Ratio (SNR) achieved by traditional array imaging systems is usually unsatisfactory because of different types of interferences, including backscattering effects and background noise. Related to this, the performance of existing methods for noise filtering are bounded by the classical detection signal-to-noise ratio. In particular, and there is no effective filtering method when the wavelength of the signal and noise is the same. To address this challenge, this study presents a novel approach to enhancing the Signal-to-Noise Ratio (SNR) of array imaging through the use of quantum state engineering. At the transmitter, we modulate the signal photons with orbital angular momentum to distinguish them from the photons of noise without orbital angular momentum. This modulation makes the signal and noise have differences in spatial intensity distribution. Due to this spatial difference, the signal and noise can be non-destructively separated after passing through the filter at the receiver, which gives enhanced SNR. The results show that this method can effectively filter out the noise with the same wavelength as the signal, and can improve the performance of array imaging detection.

A pulse position modulation (PPM) algorithm is designed and implemented to counter atmospheric turbulence interference in free-space optical (FSO) communication. A homemade turbulence simulation device based on thermal wind has been constructed to simulated a atmospheric turbulence channel, and it has been utilized to check the performance of the FSO communication system in atmospheric turbulence conditions. Both the signal modulation schemes of 4-ary pulse position modulation (4-PPM) and non-return-to-zero (NRZ) on-off keying (OOK) are implemented and compared in the system, and their corresponding modulation and demodulation algorithms have been realized using the field-programmable gate arrays (FPGA). To verify the effectiveness and practical performance of the PPM algorithm, extensive experiments have been carried out on the FSO communication system under laboratory- simulated atmospheric turbulence conditions, and the bit error rates (BER) of the PPM and OOK modulation schemes have been obtained and compared. The experimental results in the simulating atmospheric turbulence channel show that the PPM modulation system designed in this study yields a lower BER than the OOK modulation system under different turbulence intensities. Furthermore, as the turbulence intensity increases, the BER’s improvement of the PPM modulation system becomes more remarkable. The research results indicate the FSO communication system with PPM modulation possesses superior performance in an atmospheric turbulence channel.

The photodetector module is a key optoelectronic device that converts the optical signal of the sensing optical path of FOG (Fiber Optic Gyroscope) into electrical signal and amplifies the weak signal, which greatly affects the accuracy and performance of FOG. High precision FOG requires detector components with low noise, high sensitivity, high responsiveness and wide dynamic range. In this paper, the zero voltage and the noise voltage of the traditional detector module are analyzed, and a new detector design scheme is proposed. The photovoltaic operating mode is selected and the signal is processed by difference. At the same time, the noise such as dark current is suppressed by controlling the temperature. The test results show that the variation of the zero voltage at full temperature (- 50°C～75°C) of the new detector assembly is reduced from 50 mV to no more than 3 mV, and the noise voltage is reduced from 0.8mV to 0.5mV. In practical application, the random walk coefficient of the high-precision FOG is reduced by 17.3%, and the full temperature bias stability is improved by 32.6%. The new detector assembly is of great significance for improving the accuracy and full temperature performance of the high-precision FOG.

Gold-coated photoresist grating (GCPG) is commonly employed in high-power femtosecond laser systems for its broadband and simple structure. The pyrolysis and low heat conductivity of photoresist substrates are well known to result in a low GCPG laser damage threshold, which restricts the power increase of laser systems. Gold-coated fused silica grating (GCFSG) has a high threshold potential since the grating pattern is transferred from the photoresist to the fused silica substrate by etching. In this paper, a rectangular GCFSG with a period of 1740 l/mm was designed and fabricated. Using rigorous coupled-wave analysis (RCWA), the ideal slot form for GCFSG with high diffraction efficiency was designed. After a comprehensive analysis of the impact of gold plating coating flaws on efficiency, iterations of the coating process were carried out to optimize the slot shape. For these GCFSG samples, magnetron sputtering was used as the gold deposition process and the samples had a bandwidth of at least 150 nm with the -1st-order diffraction efficiency of 93% around the central wavelength of 800 nm. The measured efficiency results were compared with our simulation calculations and good agreement was achieved. After being damaged by lasers, GCFSG can be reused with good economics by being cleaned and then gold-coated.

In this paper, the metasurface is designed based on silicon nitride material that can generate vortex beams at 830nm, and its corresponding performance is also studied. Firstly, the vortex metasurface based on cross-shaped nanopillars is designed with propagation phase. By changing the topological charge and focal length, two types of vortex metasurfacesare designed to produce vortex beams at the same focal length with different topological charges and at the different focal lengths with the same topological charge. Secondly, a double-layer metasurface is further designed with propagation phase for the lower layer and Pancharatnam–Berry phase for the upper layer. Spin-related vortex beams with different focal lengths and topological charges can be generated when left-handed circularly polarized light (LCP) or right-handed circularly polarized light (RCP) is incident on this double-layer metasurface, respectively. This study provides some ideas for the design of vortex metasurfaces in the near infrared.

In this paper, we mainly study the problem of electron cloud diffusion in high-speed ultraviolet photonic imaging detectors. In this paper, the size of the electron cloud transmitted by the microchannel plate and the anode in the high-speed ultraviolet photon imaging detector is studied by simulation, including the bias angle, pore diameter, voltage (U) and distance between MCP and anode (l) on the electron cloud received by the anode. the diffusion radius of the electron cloud increases with the increase of the bias angle, and the voltage (U) and the distance (l) between the MCP and the anode on the electron cloud received by the anode. The research shows that the diffusion radius of the electron cloud increases with the increase of the bias angle, the diffusion radius of the electron cloud. When U is larger, the energy of electron cloud is also higher. When the voltage increases to 1900V, the electron movement speed increases linearly with the increase of U. Moreover, the diffusion distance of the electron cloud radius increases with the increase of the transmission distance l. When the distance is 2 mm, a maximum electron diffusion radius is obtained. When the bias angle is 10°, the pore diameter is 10um, the voltage is 2000V, and the distance l is 0.5mm, the diffusion ratio of the electron cloud is 5.5.

The rapid development of space technology has propelled space-based on-orbit servicing into a new and independent research domain. Fueled by advancements in modern aerospace technology, the application of on-orbit servicing and operations has experienced further expansion. This paper provides an overview of the current state of space-based onorbit servicing technology both domestically and internationally. Emphasis is placed on elucidating the existing and future on-orbit servicing technology development plans of Western countries, led by the United States, as well as the current status of on-orbit servicing technology development in China. Furthermore, an analysis of the prospective directions for the future development of on-orbit servicing technology is conducted.

A high-power and widely tunable Ti: sapphire laser dual-end pumped by a 10 kHz 532 nm pulsed laser with an output wavelength of 720–890 nm was demonstrated. An effective thermal management was achieved by a dual-end pumping scheme and an elaborate symmetrical flat cavity design, which greatly improved the upper limit of pump power. When the pump power was 41.5 W, a maximum output power of 10.36 W at 800 nm was obtained with a linewidth of 2 nm and a pulse duration of 17 ns. The corresponding conversion efficiency was 25 %.

The dual-frequency coherent lidar (DFCL) has advantages of anti-interference, stability, and can obtain low Doppler frequency shift in high-speed dynamic target detection. A performance evaluation model of DFCL is established for remote Gaussian rough object detection. The detection ability is closely related to laser echo characteristics, especially the intensity and coherence. The laser beam radius on the far field increases with the decay of the emitted laser pulse coherence, and the atmospheric turbulence reduces the coherence further. The intensity utilization factor is defined and calculated. The decoherence effects of rough surfaces are calculated via the complex coherence degree under typical roughness parameters and laser wavelength. Moreover, the Doppler frequency shift is proportional to dual-frequency difference ∆f, but the signal-to-noise ratio (SNR) decreases with larger ∆f duo to the coherence reduction of dual-frequency laser, and the optimal dual-frequency difference ∆fm selection criteria is determined for practical applications; and the system efficiency reduction factor are calculated and compared under typical detection parameters. Finally, the combined effects of laser source coherence, atmospheric turbulence, optical parameters and ∆f on the SNR improvements are analyzed considering dual-frequency and single frequency lidar systems. This research is of significance to reveal the dual-frequency coherent detection process and the optimization method of coherent lidar systems.

An algorithm is designed to realize the digital representation of long distance transmission laser spot energy intensity distribution, due to the current situation that the energy intensity of long distance transmission laser spots cannot be accurately represented in the laser system. A definite number is obtained by image processing and program calculation of a laser spot. The simulated laser spots are calculated and contrasted to verify the universality and applicability of the algorithm. The calculation results show that the spots size have negative impact on the representation results. Using this algorithm, the adjustment criterion of the long distance transmission laser spots in the laser system can be set more conveniently.

In this paper, a preliminary demonstration of all-fiber coherent beam combining (CBC) with active polarization-and- phase control is proposed. The CBC system was composed of two laser channels combined with a fiber coupler. One channel utilized non-polarization-maintained (non-PM) fiber, and the state of polarization of laser was controlled by using a dynamic polarization controller (DPC). The other channel adopted polarization-maintained (PM) fiber, and the phase of laser was controlled by using a phase modulator. In the central controller, hill-climbing algorithm and stochastic parallel gradient descent (SPGD) algorithm were applied for phase-locking and polarization-locking respectively. With this system, 82.3% of combining efficiency was demonstrated, the extinction ratio of the combined laser was 97.3% and the phase-locking efficiency reached 96.05%.

In a recent experimental study, we investigated a homemade distributed side-coupled cladding-pumped (DSCCP) fiber using a master oscillator power amplifier (MOPA) configuration and tandem-pumping technique. During the experiment, we observed an abnormal behavior of the residual pump power from the counter port of the pump core. This abnormal behavior exhibited a threshold-like characteristic, with both the residual power and corresponding power ratio to injected pump starting to increase exponentially above a specific value. Specifically, when the pump power injected into the system ranged from 7.2 kW to 11.77 kW, the corresponding residual power ratio increased from 4.05% to 11.01%. Simultaneously, the signal optical-to-optical conversion efficiency decreased from 84.11% to 75.33%. This sudden appearance of the phenomenon significantly limits the ability to further scale the power of the system. However, the underlying mechanism causing this abnormal behavior remains unclear and requires further investigation.

The influence of mode instability (MI) on polarization extinction ratio (PER) has been investigated in a 2 kW level polarization-maintained (PM) fiber laser system with backward-pumped configuration, and the phenomena is different from the existing observation in forward-pumped PM fiber amplifiers. During the experiment, with the onset of MI, none decrease of PER has been observed, revealing that the MI effect has little impact on PER in backward PM fiber amplifiers. The discrepancy induced by the pump configuration has been theoretically analyzed, and the origin is attributed to the longitudinally-distribution difference of high order mode induced by the MI effect.

Metal/dielectric coated semiconductor lasers with sub-wavelength dimensions have shown promising applications in photonics integrated circuits and on-chip optical interconnects. In this study, we optimize the structure of circular InAlGaAs/InP nanocavities by employing the finite-difference time-domain (FDTD) numerical simulation method. It was found that, the quality factors of monopole modes in a cavity with radius of 250 nm can be over 1000 after structure optimization. Furthermore, the far-field characteristics of resonant modes in the cavities with different radius were studied. For the monopole modes, the divergent angle of far-field distribution decreases along with the increase of longitudinal order. Meanwhile, the cavity radius has a significant effect on the far-field distribution for monopole modes. For the dipole modes, the far-field distribution concentrates on a small angle range which is much better than that of monopole modes, and the effect of cavity radius on the far-field distribution is small. The research results of this study provide valuable insights for the design and fabrication of efficient and high-performance nano-lasers.

Over the past decade, numerous types of launch vehicles, exceeding a dozen in total, have achieved their maiden flights. Through a meticulous analysis and evaluation of these launch vehicles. The global space industry has ushered in a new era marked by complete commercialization, innovation-driven advancements, and the integration of military and civilian efforts. Taking into account the evolving demands of commercial satellites worldwide, particularly the deployment of space station cargo supplies, low-orbit Internet constellations, and flight transportation, there is an urgent need to augment the payload capacity and carrying efficiency of launch vehicles. Enhancing launch efficiency is also paramount. Consequently, it is imperative to construct a series of launch vehicles that possess comprehensive mission capabilities and exhibit a first-class technological standard. These endeavors will effectively cater to the ever-increasing requirements of the industry.

With the improvement of the lithography resolution, the immersion scanners have a higher demand for the performance of the illumination pupil such as energy balance and polarization performance. The method of pupil generation by the immersion scanners are mainly by adjusting the angle distribution of micromirror array (MMA). Below the 40nm technology node, the influence of the polarization characteristics of the light on the imaging of the light must be considered. A micro-mirror select and angle set algorithm of freeform pupil illumination systems in immersion scanners is proposed that can guarantee the key characteristics of the freeform pupil, ensuring the energy balance of the pupil in the unpolarized state and the energy balance in the polarized state. The energy balance in the unpolarized state is related to the eccentricity of the light, and the energy balance in the polarized state and eccentricity of the light. In order to verify the accuracy of the algorithm, based on the unpolarization state of freeform pupil illumination optical simulation model and the polarization state of freeform pupil illumination optical simulation model, through the simulation found that the unpolarization state of energy balance and polarization energy balance greatly improved, reduced to 0.08%.

The high power diode lasers emission wavelength around 7xx nm are highly significant as pump sources for developing Rb alkali metal vapor laser and solid-state lasers based on thulium Tm: YAG. In this paper, 780 nm diode laser single emitter and bar have been designed and fabricated. The epitaxial layers were prepared by the metal organic chemical vapor deposition technology. GaAsP and GaInP were used as the quantum well and waveguide layer, respectively. The confinement layers were AlGaInP material with low refractive index. An amorphous ZnSe passivation layer was deposited on the laser cavity facets using ultra-high vacuum cleavage and passivation technology. The single emitter device with 150 μm width and 4 mm cavity length did not show the COMD phenomenon until 16.3 W continuous-wave output at 15 A. Meanwhile, The slope efficiency reached 1.27 W/A, and the electro-optic conversion efficiency was 58%. The divergence angle of slow-axis was 9.9°. In addition, the 1-cm laser bar with lateral emitter fill factors of 30% reached continuous-wave 180 W output power at 192 A, the electro-optic conversion efficiency was 50.7%, and the spectral width was 2.2nm.

This paper introduces the simulation of the thermal focal length brought by the Conduction Cooling End-Pumped Slat(CCEPS) laser amplification module under the action of thermal stress. Through simulation analysis, it is found that the thermal focal length of CCEPS lath crystal is affected by two factors, temperature distribution and stress distribution. One of these two factors brings a positive lens effect, the other may bring a negative lens effect, and it may also bring a positive lens effect at the same time. In order to find out the law of thermal lens effect in CCEPS module, a comprehensive simulation analysis of CCEPS module is carried out. This paper provides a strong theoretical support for further experimental verification.

The diffraction-limited multiplier factor β is one of the important indicators for evaluating the energy transfer performance of an optical system. It can reasonably evaluate the beam quality and reflect the actual laser beam energy transfer efficiency and focusability. Starting from the basic concept of β factor, this paper discusses the calculation method of β factor, analyzes the characteristics of β factor, and discusses the engineering application method of β factor based on actual engineering experience, which provides a reference for high-energy laser β factor engineering testing.

This paper introduces the thermal effect of the slab amplifying module in the high-energy solid-state laser, mainly simulates the influence of the thickness of the metal indium layer on the welding surface of the slab and the heat sink on the thermal effect of the slab, and analyzes the effect of different thicknesses of the indium layer on the thermal effect of the slab. The thickness of the metal indium layer used in the calculation is 10μm, 40μm and 80μm respectively. This paper provides a powerful reference for the engineering application of high-power and high-beam-quality all-solid-state laser systems.

This paper uses an ultrafast laser with a wavelength of 532nm and a pulse width of 10ps to conduct cutting process experiments on typical grades of CFRP materials in the aerospace manufacturing field, such as high-modulus CFRP and high-strength CFRP. After optimizing laser parameters and processing paths, a high-quality processing effect with minimal heat affected zone was obtained, and the fracture morphology characteristics and mechanical properties of the processed specimens were studied. The results indicate that under the laser wavelength, pulse width, and processing parameters selected in this paper, the morphology of the cut edge of typical CFRP materials was observed without visible heat affected zone through 200x optical microscope magnification, and the processed section was bright and burrfree, the fiber bundle section was neat, and the resin section was smooth through 2000x scanning electron microscope observation. Through the mechanical tensile testing, compared the ultrafast laser processed tensile specimens with the traditional mechanical cutting and punching tensile specimens, the ultrafast laser processed specimens of many typical grades of CFRP materials all have higher tensile mechanical properties, which also proves that the ultrafast laser pulse width and wave band used for CFRP materials have excellent processing quality, and are suitable for promotion and application in the aerospace manufacturing field. Finally, this paper introduces the typical applications of ultrafast laser processing CFRP in aerospace products.

Tunable and low-power microcavities play a vital role in facilitating the development of large-scale photonic integrated circuits. Among various tuning methods, thermal tuning has gained significant popularity due to its convenience and stability, especially in the fields of optical neural networks and quantum information processing. In recent years, graphene thermal tuning has emerged as a promising technique, offering both tunability and power efficiency by eliminating the need for thick spacers to prevent light absorption. In this study, we propose and fabricate a silicon-based on-chip Fano resonator with graphene nano-heaters. This innovative Fano structure incorporates a scattering block and can be easily manufactured in large quantities. Experimental results demonstrate that the resonator exhibits desirable characteristics, including a high quality factor of approximately 31000 and a low state-switching power consumption of around 1 mW. The temporal responses of the microcavity exhibit satisfactory modulation speed, with a rise time of 9.8 μs and a fall time of 16.6 μs. The findings of this research offer an alternative solution for the future development of large-scale tunable and low-power-consumption optical networks, with potential applications in optical filters and switches.

With the rapid development of industry, semiconductor, aerospace and other industries, the device processing size is getting smaller and smaller, and the positioning accuracy of high-end equipment is becoming higher and higher in recent years, the development level of precision positioning technology, to a certain extent, characterizes a country's scientific and technological strength, and reflects the country's comprehensive national strength. From aviation and aerospace to the lithography industry directly related to various chips, precision engineering technology plays an important role in them. Control accuracy is often a very important indicator to measure whether the control environment meets the requirements. In this paper, permanent magnet synchronous linear motor is used to compare the influence of various algorithms on the control accuracy of the motor. This paper mainly conducts in-depth research on the control algorithms and compares various performance indicators of different algorithms in the same working environment. First of all, the control principle and core points of PID control algorithm, SMG sliding mode control algorithm and ADRC active disturbance rejection control algorithm are briefly described. The control system block diagram of these three control algorithms is given, and the advantages and disadvantages of these three control algorithms are expounded. The permanent magnet synchronous linear motor control system modeling is carried out on matlab/simulink. Then use matlab/simulink to carry out these three control algorithms for the motor control simulation and control experiment, modify the parameters and then compare the simulation results, and point out which algorithm is better in the control environment.

Air tightness and particle impact noise detection (PIND) results are important indicators for evaluating special optoelectronic devices, which are determined by the level of energy storage welding packaging technology. This article focuses on the existing energy storage welding packaging process of special optoelectronic devices, analyzes the reasons for the formation of particles inside the devices during the energy storage welding process, and optimizes the energy storage welding process of the devices to meet the requirements of airtightness and PIND qualification rate of the devices.

Microchannel plate (MCP) is an important charged particle electronic multiplier. Usually, electrons as the charged particles entered the input-end and strike the inner wall of the microchannel, producing an electron multiplication. Once the input particles changed into high-energy ions, colliding and sputtering effects would occur in the secondary electron multiplication generation processing of directly bombard on the microchannel plate. A poor ion bombardment-resistance property became the main bottleneck for the detection of high-energy ions of microchannel plate. In this paper, the (SrO, ZrO₂) doped lead-silicate glass was as the cladding glass of microchannel plate and explored in the ion bombardment-resistant properties. Argon/cesium ion gun and laser confocal microscope were applied to investigate the ion etching and etching surface morphology of the lead-silicate glass microchannel plate, respectively. It impacted that (SrO, ZrO₂) doped lead-silicate glass certainly benefited the ion-bombardment resistance of the MCP.

Microchannel plate (MCP) is an advanced charged particle multiplier consisted of an arrayed microchannels glass-based material, widely used in the fields of night vision intensification, time of flight mass spectrometer, and electron microscopy. For the detection of high-energy ions, inadequate resistance of ion bombardment became the main bottleneck of microchannel plate. The cladding glass was the inner-wall of microchannels and determined the foundation of the microchannel plate. In this paper, the microchannel plate with (SrO, ZrO2) doped lead-silicate cladding glass was explored in the ion bombardment-resistant properties. Cesium ion gun, laser confocal microscope, and Vacuum Photoelectron Imaging Test Facility (VPIT) were applied to investigate the ion etching, surface morphology and the lifetime of the lead-silicate glass microchannel plate, respectively. The test results are as follows: the accumulative output charge of microchannel plate with the (SrO, ZrO₂) doped lead-silicate glass and the traditional lead-silicate glass was ≥19.25 C and 3.21 C, respectively. It impacted that (SrO, ZrO₂) doped lead-silicate glass certainly benefited the working life of the MCP.

In order to distinguish the direction of the moving object, a frequency-shifted laser Doppler velocimetry system was designed using acousto-optic modulation technology. Based on the heterodyne detection method, a fixed frequency is introduced by shifting the frequency of the reference beam, so that the received signal changes about the fixed frequency. In addition, the correlation detection technology is applied to signal processing in order to reduce the signal-to-noise requirements of laser Doppler velocimetry. Finally, the feasibility and speed measurement accuracy of the system are tested by using a turntable as the speed source. The experimental results show that the frequency-shifted laser velocimetry system can discriminate the velocity direction effectively.

Two-wave mixing interferometry based on photorefractive crystals stands out among many techniques for monitoring dynamic strain because it can provide multiple dynamic sensing and does not require electronic feedback to actively compensate for any quasi-static drift. However, the traditional optical signal sensing processing system has shortcomings such as large, occupied space, various types of optical components, and complex optical path structure, which is not conducive to practical applications. Thanks to the development of photonic integrated circuits, photonic integrated can effectively solve these shortcomings. In this paper, based on the experimental study of two-wave mixing interferometry in InP:Fe spatial optics configuration, a photonic integrated two-wave mixing photorefractive interferometer is designed, which consists of curved waveguide, directional couple, unbalanced Mach-Zehnder interferometer structure, crossed waveguide, electrodes, etc. To minimize the loss of light in transmission and achieve the best demodulation performance for a two-wave mixing photorefractive interferometer, each structure is optimized by finite element method simulations. The feasibility of the optimized structure is verified in theory and the demodulation curve of transmitted signal light varying with time is obtained.

Background oriented system (BOS) technology is widely used for measuring flow field density information. The fingerprint information of high-speed target flow field can be calculated with the digital image correction (DIC) method. However, these traditional DIC algorithms are unable to obtain large-scale features of target flow fields and costing high computational complexity. To deal with those problems, a method combination of dual tree complex wavelet transform and optical flow (DTCWT-OF) is proposed. The proposed method adopts a much sparser gradient divergence regularization to obtain much more sparse statistical characteristics of the target flow field, and utilize the prior knowledge of the target flow field fingerprint information. Meanwhile, the reconstruction method is processed in the wavelet transform domain. Compared to traditional DIC methods, the experimental results show that the proposed method improves the SNR by 5dB and can achieve quasi real-time reconstruction.

With the integration of the Internet of Things and artificial intelligence technology, the amount of data is increasing exponentially. However, the traditional von Neumann architecture makes the processing of nonstructural visual data inefficient. In view of this, many neuromorphic visual systems have been proposed. However, the data transmission process through the photoreceptors to the computing unit still results in data redundancy and additional power consumption. Therefore, it is necessary to develop intelligent visual systems capable of performing calculations within pixels, which requires the development of photodetectors with sensing, memory and processing functions. Here, a neuromorphic synaptic phototransistor based on MoS₂ is prepared. The proposed phototransistor shows synaptic properties, including short-term/long-term synaptic plasticity, paired-pulse facilitation and forgetting properties. As a proof of concept, it is demonstrated that the image preprocessing and memory ability of the intelligent visual system based on this neuromorphic phototransistor. The proposed phototransistor can be used as a photoreceptor and a biological synapse in an intelligent visual system, which shows its potential application in the efficient processing of visual information.