In this paper, a hole-triggered Si avalanche detector (APD) was prepared based on CMOS process. And the breakdown effect model of the hole-triggered avalanche device was established based on the breakdown characteristics of the device at different operating temperatures. Based on the avalanche breakdown model and the breakdown voltage test results, the parameter of breakdown electric field versus temperature (dE/dT) was obtained by fitting the curve. The breakdown voltage and temperature are positive temperature coefficients at 250~320 K. And the device undergoes avalanche breakdown dominated by dV/dT=23.3 mV/K. The value is determined by the width of the multiplication region as well as the carrier collision ionization coefficient. At 50~140 K operating temperature, the breakdown voltage is a negative temperature coefficient and the device undergoes tunnel breakdown with dV/dT=-58.2 mV/K. The value is mainly influenced by both the spatial extension of the electric field in the avalanche region and the peak electric field.

Junction temperature and carrier temperature are widely concerned as significant parameters affecting LED luminous efficiency. The variation rules of electroluminescence (EL) spectrum and carrier temperature with junction temperature of GaN-based blue micro-LED were investigated in this paper. The accurate real-time measurement of junction temperature and EL spectrum of GaN-based blue micro-LED at current densities of 0.04~53.4 A/cm2 were conducted by using the chip design with a built-in integrated sensor unit, and the range of the low-temperature end of the junction temperature measurement was extended to 123 K using the forward voltage method. The results show that the linear slope of junction temperature and forward voltage change due to carrier leakage and series resistance at low temperature. The high-energy slope method was used for EL spectrum to calculate the carrier temperature at different current densities. It is found that the carrier temperature and junction temperature can be approximately fitted by a quadratic equation within the range of junction temperature and current density under study. And the law of the variation of the carrier temperature with junction temperature and current density was analyzed and explained.

Space astronomical detection commonly uses CCD as the main detector. However, the extreme radiation environment can affect CCD performance and, in turn, impact data acquisition. To gain a deeper understanding of the mechanisms impact on data acquisition, in this paper, based on the SRH theory, the defects effects on charge capture and release during transfer was discussed. A transfer model based on the CCD electrode level was established, and the operation principle of defects under different conditions was simulated. The model was used to simulate STP timing, and to discuss the impact of timing on data acquisition in actual use and the method of extracting relevant parameters from STP timing data, as well as the relationship between the parameters. The model assists in understanding the impact of radiation defects on CCD data transfer, simulating STP timing, and utilizing STP timing to acquire CCD defect parameters in actual applications.

In this paper, an infrared thermal detector based on a metamaterials structure is proposed. It achieved the detection of radiation by utilizing the local field enhancement effect of optical metamaterials and the temperature-sensitive properties of pyroelectric materials. A finite element analysis method was utilized to analyze the infrared absorption characteristics and electromagnetic field properties of the metamaterial absorber, as well as to analyze the thermal properties of the coupled structure of the metamaterial absorber with a pyroelectric material (LiTaO3). The results show that the designed metamaterial absorber can modulate the peak wavelength in the range of 3 to 15 μm (mainly covering the atmospheric window (8~14 μm)), with an absorbance rate of 99.9% and a bandwidth of 0.2 to 1 μm. When the detector size is 23 μm×23 μm, the steady-state temperature increase of the detector is 0.311 K, which is about 21 times higher compared to similar studies. Improved infrared heat detector has significant temperature response, and it is applicable to thermal imaging and sensing in uncooled mid-infrared and far-infrared wavelengths at the large-scale image element level.

A 90° optical hybrid based on an InP 4×4 multimode interference waveguide (MMI) was designed and fabricated. The optical hybrid was fabricated with InGaAsP waveguide layer, InP cladding layer and InP substrate. The width of the single mode waveguide was set to be 2.6 μm, and the length and width of MMI were set to be 844 and 20 μm, respectively. Three dimensional beam propagation method (3D BPM) was used to simulate and analyze the process error tolerance of refractive index, thickness, width and length of wavwguide materials. It is found that optical hybrid’s insertion loss is less than 1 dB and phase deviation is less than 5° in the wavelength range of 1 535~1 565 nm, which is consistent with the simulation result.

A single mode-hollow core-single mode (SHS) fiber microstructure strain sensor was proposed. A wavelength strain relationship model was established using the beam propagation method, and the strain and temperature characteristics of the SHS were experimentally studied. The experimental results showed that the tensile strain sensitivity in the range of 0~340 and compressive strain sensitivity in the range of -340~0 were as high as -4.19 pm/ and -4.26 pm/, respectively, with linearity values of 0.997 1 and 0.998 1, respectively. In the range of 20~70 ℃, the temperature sensitivity was 9.6 pm/℃, and the linearity reached 0.990 9. This sensor is simple to make and has a high strain sensitivity.

In order to improve the output accuracy of fiber optic gyroscope, the BP neural network model optimized by the beetle antennae search algorithm (BAS) was used as the base learner, and the Bagging parallel integrated learning algorithm was used to establish a BAS-BP-Bagging temperature compensation model, and a temperature compensation experiment was conducted for a certain model of fiber optic gyroscope. The experimental results show that under the temperature change environment from -40 ℃ to +60 ℃, the temperature drift of the fiber optic gyroscope after compensation is reduced by nearly 80% compared with that before compensation, 55% compared with the polynomial compensation algorithm, and about 30% compared with the BP neural network compensation algorithm. And the model shows superior generalization performance in the compensation of fresh samples.

A perturbation sensor based on the detection of a weakly coupled few-mode multi-core fiber (FM-MCF) specklegram was proposed and experimentally demonstrated. The sensor has a cascaded fiber structure consisting of a “single mode fiber-multi-mode fiber (MMF)-multi-core low-mode fiber." After the light field of a single-mode laser passes through the MMF, all seven cores in the FM-MCF can be illuminated, and an image with seven sub-specklegrams can be received by a camera at the end of the FM-MCF. In an experiment, perturbation was applied to different positions of the FM-MCF and specklegrams were collected at the same time. Based on the strong-coupling characteristic of the core and weak coupling between the core, the fiber structure achieved a high precision classification of 99.46% for 15 disturbance locations, with a spatial resolution of 3 cm, which was much higher than the results for disturbance locations when using only MMF specklegram detection. The capability of the sensor to detect the perturbation position and intensity simultaneously was also tested, and the recognition accuracy was close to 100%. The experimental results showed that the proposed sensor has the advantages of low cost, a simple structure, easy demodulation, and high precision.

A CMOS readout IC for five-spectrum-band TDICCD detector was developed to address the digitization and high-speed readout requirements of 3D integrated multispectral TDI-CMOS image sensors and to solve the matching and consistency problems of the overall layout, physical size and I/O interface with the TDICCD detector. A new column single-slope ADC architecture was designed for this readout IC, which used multi-phase ADC clock and supported correlated multiple sampling (CMS), realizing the digitization and high-speed output of TDICCD output signals and effectively improving the dynamic range and noise performance of the TDICCD detector. The tests after tapeout show that the readout IC functions normally, the imaging results of the integrated TDICCD detector is good and the new column ADC works fine. The readout IC outputs 14 bit data with a minimum line readout period of 9.5 μs, and the CMS reduces output noise effectively, realizing the high-precision digital processing and high-speed output of the TDICCD output signal, and meeting the requirements of 3D integrated TDI-CMOS image sensor development.

Large field-of-view (FOV) lens is an essential component in imaging systems. To realize the large FOV, conventional optics requires the combination of multiple lenses into a lens group to correct the aberration caused by different angles of incident light. In this paper, a near-infrared metalens is designed and fabricated, which consists of a single-layer metasurface and a metal aperture distributed on both sides of the substrate. The device can suppress aberration effectively and realize a 120° large FOV imaging at the wavelength of 940 nm. Experiments have demonstrated that the fabricated device exhibits good focusing performance within the designed FOV range, with an average experimental focusing efficiency of 45%.

A passive Q-switched erbium-doped fiber laser based on a saturable absorber of single-walled carbon nanotubes coupled with a Sagnac loop is proposed. The output laser properties of the laser was experimentally investigated. Single-walled carbon nanotube saturable absorbers were created by light deposition with a 75% transmittance. A Q-switched laser was built to modify the resonators Q value based on the single-walled carbon nanotubes saturable absorption properties. When the Sagnac loop filter was placed inside the optical fiber ring cavity, the Q-switched pulses could achieve fine filtering thanks to the filtering effect produced by the Sagnac loop structure. The Q-switched lasers operating threshold is 800 mW. When the pump power is 830 mW, the laser can produce a stable 1 530.4 nm laser output with an output power of 12.3 mW. The repetition frequency is 210.7 kHz, the corresponding pulse period is 4.76 μs, the pulse width is 2.19 μs, and the maximum pulse energy is 58.37 nJ .

A method for suppressing backscatter noise based on transient process optimization is proposed. This method optimizes the parameters of triangular wave modulation and demodulation to address the serious effect of backscatter noise on a resonant fiber optic gyro (RFOG). The method optimizes the phenomenon of the transient process present in triangular wave modulation by partial sampling and mean filtering to improve the rejection ratio of backscatter noise and the linearity of the workspace of the demodulation curve without changing the optical and electrical hardware of the gyro. The results of experiments conducted with a prototype showed that the noise suppression method based on transient process optimization could reduce the duty cycle of the transient process from 64.3% to 12.1%, and the suppression ratio of backscatter noise reached 46.8%. At the same time, the workspace of the demodulation curve had a linearity of 99.6%. The method based on transient process optimization efficiently improved the suppression of backscatter noise in an RFOG, along with the linearity of the workspace of the demodulation curve.

Based on Python language, a semiconductor laser diode simulation EDA program with UI interface was written. The program could set the material composition of the active area of the semiconductor laser diode chip, analyze the material parameters and calculate the waveguide refractive index, draw the refractive index distribution curve and the light intensity distribution curve, calculate the energy band structure and gain characteristics of the active area of the chip, and draw the optical gain spectrum curve under different carrier concentrations. Using the EDA program, the semiconductor laser diode chip with 791 nm wavelength was simulated. The chip with light-emitting region width of 190 μm and cavity length of 4 mm was fabricated and it has a peak power of 16.25 W at 15 A current.

The traditional on-chip global ramp generator circuit is significantly affected by process, voltage, and temperature (PVT), resulting in ramp signal distortion and poor linearity. Moreover, calibration becomes difficult owing to parasitic effects. Therefore, in this study, we introduced an adaptive ramp generator that resists PVT variations. We fine-tuned the ramp using a successive approximation algorithm and a fixed-step search method and achieved a two-point slope correction. The ramp calibration circuit included a resistive DAC (RDAC), current-mode DAC (IDAC), logic control, dynamic comparator, and other modules. The average calibration period for the adaptive ramp generator was found to be approximately 1.143 ms. Post calibration, DNL of the adaptive ramp generator was +0.002 07/-0.001 15 LSB and INL was +0.675 5/-0.388 7 LSB. Under various PVT conditions, the calibration voltage error was less than 1.5 LSB and power consumption was as low as 1.155 mW. Compared with traditional ramp generators, the proposed adaptive generator is advantageous in terms of higher precision and lower power consumption.

A Ge-based phototransistor with programmable characteristics based on the memristor structure was designed and prepared, which consisted of two back-to-back memristors structured with Ni/Ge/GeOx/Al2O3∶HfO2/Pd, sharing the same resistance switch layer GeOx/Al2O3∶HfO2, substrate Ge and bottom electrode Ni. The design of the resistance switch layer was the key to realize the function of phototransistor. The two top electrodes Pd were used as the source-drain electrodes of the phototransistor, and the area between the two memristors was used as the gate of the phototransistor to receive regulation from external illuminant. The electrical and optical response characteristics of a single Ge-based memristor were explored. The output and transfer characteristics of the phototransistor based on gate-control from illuminant were realized. Furthermore, the scientificity and feasibility of this design was verified through exploring the device physics and mechanism. The phototransistor has advantages of non-volatility and compatibility with standard CMOS process, which can effectively simplify the process and reduce fabrication cost. This phototransistor can provide reference for the next-generation of optoelectronic chip to some extent.

A high-speed imaging readout circuit for a linear-mode HgCdTe APD was proposed. A resistive feedback transimpedance amplifier (RTIA) with adjustable transimpedance gain was used in the image element to realize the real-time linear conversion of the photocurrent, and the phase margin of the RTIA was optimized using the capacitive compensation method to solve the output oscillation phenomenon at low gain. The results showed that the RTIA transimpedance gain within the image element was 100~140 dB, the GBW could be improved by 1014 times, and the output delay of the image circuit was lower than 1.6 ns. A column-level time-of-flight measurement circuit and a two-stage time-to-digital converter were used for the wide-area coarse quantization of the time-of-flight and high-precision fine quantization, respectively. The measurement range was up to 1 530 m, with a measurement accuracy of 106.5 cm and a linearity of greater than 99.99%.

A highly efficient exciplex with significant thermally activated delayed fluorescence characteristics was realized by combining the electron donor of mTPA-PPI and the electron acceptor of PO-T2T. The exciton dynamics processes, such as the reverse intersystem crossing (RISC), prompt fluorescence, and delayed fluorescence of mTPA-PPI∶PO-T2T were explored through the time-resolved spectra technology. A high-performance phosphorescent OLED based on the mTPA-PPI∶PO-T2T co-host was developed. Due to an efficient reverse intersystem crossing process, the triplet exciton utilization was improved, effectively boosting device efficiency and alleviating efficiency roll-off at high current densities. The maximum current efficiency, power efficiency, and external quantum efficiency of the red phosphorescent device based on the co-host are 20.3 cd/A, 18.6 lm/W, and 11.54%, respectively, which were 1.4, 1.2, and 1.5 times that of single-host device. In addition, the maximum luminescence of the co-host device reaches 25 410 cd/m2, which is 3.9 times that of the maximum luminescence of a single-host device.

Electron-only devices with different structures were prepared by doping Liq (8-hydroxyquinolinato-lithium) into the electron transport layer Alq (tris(8-hydroxyquinolinato) aluminum). The experimental results show that the electrical properties of doped devices are inferior to those of non-doped devices with Liq/Al composite cathodes and superior to those of non-doped devices with Al only cathodes. This indicates that Liq’s doped with Alq does not show any significant “n-doping” effect. The effect exhibits dual roles: Liq molecules dispersed at the Alq/Al cathode interfaces after doping display as electron injection layers, which enhances the device currents by enhancing electron injection; those in the bulk of Alq after doping have a detrimental effect on electron transport due to their own poor conductivity, consequently decrease the device currents. In the tests of electroluminescent devices, the doping of Liq shows a similar behavior. The performance of Liq-doped device is between the non-doped devices with Liq/Al cathode and Al cathode structures, with maximum current efficiencies of 3.96, 4.27 and 2.27 cd/A for the three devices, respectively, and no additional changes caused by charge transfer are observed in the absorption and photoluminescent spectra.

Currently, 1 060 nm semiconductor lasers are widely applied in areas that include space LiDAR and high-energy laser systems. Because of the high stress of InGaAs on a GaAs substrate, 1 060 nm semiconductor lasers usually have a large number of defects. In addition, 1 060 nm semiconductor lasers always have a thin waveguide layer for a large confinement factor. This produces a large cavity loss and non-radiation combination, which leads to poor slope efficiency and high-temperature characteristics. Moreover, the conventional GaAs barrier cannot effectively confine the carriers in the quantum well, which degrades its performance when the operating temperature is high. This study optimized the growth conditions and applied stress-compensated quantum wells to effectively control the stress and barrier height. Enlarging the N cladding thickness also reduced the loss in the cavity. Consequently, we invented a high-performance 1 060 nm semiconductor laser, which had a slope efficiency as high as ever recorded (0.9 W/A) at both room and high temperature. Through the buried DFB grating, it also realized operation in a single longitudinal mode with a high slope efficiency of 0.7 W/A.

In this paper, a kind of high temperature pressure sensor based on fiber grating (FBG) is designed to meet the demand of pressure detection. Through analysis and comparison, suitable packaging materials and grating coating layers were selected, structural parameters were designed, and a three-dimensional model of the sensor packaging structure was established by finite element method (Ansys Workbench). The simulation of the model was realized by applying load. The simulation results verify the rationality of the design of the pressure transfer structure of the sensor. At the same time, based on the small deflection deformation theory of thin plate, the pressure sensitivity of the sensor is calculated, the temperature compensation method of the sensor is designed, the pressure and temperature calibration experiments are carried out, the pressure sensitivity of the sensor at different temperatures is analyzed, and the effectiveness of the sensor pressure measurement and temperature compensation method at 100~450 ℃ is proved.

Three-parameter Weibull distribution has obvious advantages in fitting the life of LED lamps, but it is not easy to obtain more accurate point estimations of three-parameter Weibull distribution. At present, the commonly used parameter estimation methods, such as maximum likelihood method, moment estimation method, Bayes estimation method, etc., have complex equations, which makes the software programming very troublesome and difficult to master, and the parameter estimations may not be obtained. In view of this, a simple method to estimate the parameters of three-parameter Weibull distribution is proposed for the constant stress accelerated test in this paper. This method did not involve the solution of transcendental equation so that the software programming was quite simple, and the statistical idea was clear. The application of the method was illustrated by several case data of LED lamps under constant stress accelerated test, and the comparative analysis was made with the existing methods.

As has a small diffusion coefficient in HgCdTe material and can form a relatively stable structure, which is widely used in p-type doping of HgCdTe. As doping is an important method in the preparation of p-on-n type HgCdTe infrared detector. In view of the problem that the As activation rate cannot be accurately measured, a low temperature weak p-type annealing assisted hall test method is proposed to obtain the carrier concentration distribution. By comparing with the SIMS test results, the As activation rates in the long and medium wave liquid phase epitaxy HgCdTe material were obtained, and the influence of annealing and other processes on the activation rate after As doping was analyzed.

To achieve high-precision detection of high-speed targets and meet the application requirements of radiation environments, a CMOS image sensor architecture, pixel structure, column-parallel high-precision digitization, high-speed readout, and radiation hardening are investigated to solve problems such as compatibility issues between global and rolling exposure modes, low sensitivity and dynamics, low frame rate, and low radiation-resistance levels. Based on a single-sided column-parallel direct digital synthesis (DDS) and multi-mode compatible architecture, a 7.5 m×7.5 m, 2 048×2 048 visible-light CMOS image sensor is developed. A dual-gain pixel structure, high-frame-rate digital readout, multiple-channel selectable output, and pixel/circuit radiation hardening are adopted to achieve global and rolling exposure compatibility, high-sensitivity and dynamic imaging, high-precision digitization and high-speed output, and radiation hardening. The sensor fills a gap in domestic research on multimode exposure-compatible radiation-resistance contact image sensor (CIS) technology.Test results show that the device functions normally, the imaging output is satisfactory, and the parameters meet the expected requirements. These include the dynamic range, full well capacity, sensitivity, frame rate, and radiation resistance. These results are of great significance for high-speed, high-dynamic imaging, and radiation-environment system applications.

Polycrystalline gallium nitride (GaN) thin films were deposited at low temperatures on GaAs (001) substrates via plasma-enhanced atomic layer deposition (PEALD). The growth process, surface mechanism and interface characteristics were investigated. The results show that the PEALD temperature window is 215~270 ℃, and the average growth rate of GaN thin films is 0.082 nm/cycle. The GPC analysis was performed in terms of kinetic energy barriers and thermodynamics. It is found that the GaN thin films are polycrystalline with hexagonal wurtzite structure and have a tendency to form (103) crystal. An amorphous layer of about 1 nm is observed at the GaN/GaAs interface, which may be related to limited active sites on the substrate surface before growth and the steric hindrance effect of the precursor. Most interestingly, in the deposited GaN films, all N elements combine with Ga elements to form GaN by Ga-N bonds, but a small part of Ga forms Ga-Ga bonds and Ga-O bonds. This bonding method during deposition may be related to the defects and impurities in the GaN thin films.

The ultra-low magnetic noise (<10 nT) of alkali metal heating technique is critical for achieving ultra-high sensitivity in spin-exchange relaxation-free atomic magnetometers. In this study, a multi-objective optimization and design method for a magnetic-field self-suppression heater based on a genetic algorithm was proposed. A novel objective function model based on the Biot-Savart law was derived, and four types of parameters were used for the optimization objectives (a total of 18), including the length, width, thickness, and current direction of the heating wire, in order to obtain the best magnetic self-suppression performance from the heater. Using the finite element analysis method, the magnetic field distribution and temperature distribution in the target region were simulated and analyzed, and the results showed that the heater produced an average magnetic field of 0.02 nT/mA and an average temperature of 180.34 ℃ in the center of the target region. Experimental tests confirmed that the magnetic flux density in the target region fell within the range of 0.13~0.14 nT/mA, which indicated that the heater had a better self-suppressing performance for the magnetic field. This work contributes to further enhancing the performance of atomic magnetometers.

The Ag-based films have highest reflectivity from VIS to IR. However, the environmental stability of Ag thin films is poor and susceptible to corrosion with reflectivity reduction. Different thickness ratio of Ta2O5-SiO2 nanolaminate films were prepared by ion beam assisted electron beam evaporation (IAD). The effective refractive index and residual stress of the films were calculated. Furthermore, the nanoaminate film with Ta2O5 thickness percentage of 75% was selected, and the nano-amine structured protective layer Ag-based film system and the conventional two-layer structured protective layer Ag-based film system were further designed and prepared. Multi-band high reflectivity targets were achieved and the residual stress of the two Ag-based films were similar. After 24 hours of humidity test, the reflectance redshift of nanolaminate protection Ag-based films is less than conventional two-layers type protection Ag-based films. After 144 hours of humidity test, the degree of corrosion of the surface defects of nanolaminate protection Ag-based films is less than that of the conventional two-layers type protection Ag-based films. Combined with TEM observation results after combining FIB sample preparation, it is shown that the nanolaminate protection layers possess higher density and can provide better environmental stability for Ag-based films systems.

Integrated fiber-optic gyroscopes have considerable application prospects in miniature weapon systems and commercial domains. The integrated optical transceiver module, which is a key component of the integrated fiber-optic gyroscope, incorporates the functionalities of the light source, detector, and coupler. The coupling shift in the optical path can significantly affect the optical coupling efficiency and average wavelength, which in turn affect the zero bias and scale factor of the fiberoptic gyroscope. In this study, theoretical modeling of the spatial optical path is conducted, and the overlap integral method is used to calculate the coupling efficiency. The BeamProp method is utilized for simulation analysis to determine the coupling loss and average wavelength drift under various coupling displacements. Comparative experiments are conducted to verify the theoretical and simulation results. The findings indicate that the coupling shift in the y-direction has the most significant effect on the coupling loss, whereas the z-direction shift has the most substantial influence on the average wavelength drift. Data for the average wavelength drift at different coupling losses are provided, offering guidance for the coupling and optimization of the optical path of the integrated optical transceiver module.

Using forward and backward finite difference algorithm, the electronic states of InAs/GaSb/AlSb active region structure of antimonide cascade laser were calculated and analyzed theoretically in this paper. The effects of Hamiltonian operator order, effective mass parameter modification, internal interface state on the energy state and wave function were studied. The analyses show that the positive value of the effective mass parameter of the conduction band can effectively inhibit the generation of spurious solutions under two operator orders, and the transition energy under Burt-Foreman operator order is more reasonable. For the internal interface with the slow-change assumption, the calculated value of the transition energy is slightly higher than that of the steep interface, and the wave function profiles of the two are similar near the interface.

WO3 nanorods array films coated with SnO2 nanoparticles were prepared by hydrothermal method and electrochemical deposition method, and WO3/SnO2 heterojunction composite films were formed after annealing. The optimum preparation conditions were obtained by changing the deposition time of SnO2. The phase and morphology of WO3/SnO2 composite film were analyzed by XRD and FESEM. The photoelectric properties of WO3/SnO2 composite film were studied by electrochemical workstation. The results show that WO3/SnO2 composite film has the minimum impedance when the deposition time is 120 s. And its photocurrent density is 0.46 mA/cm2 at a bias voltage of 0.6 V, showing better photochemical properties than a single WO3 nanorod film.

In response to the challenges posed by a -type gyroscope oscillator, an anchor-free metal oscillator was optimized and improved. A finite element simulation was used to analyze the vibration characteristics of the oscillator in depth, and the oscillator modes and natural frequencies of each order were obtained. The overload characteristics of the oscillator were simulated and analyzed, and the stress and displacement performances of the oscillator under high overload conditions were obtained. The quality factor of the oscillator was further analyzed using a multi-physical field investigation. The results showed that the metal oscillator had a diameter of 15 mm, natural frequency of 12 509 Hz, and modal isolation of more than 3 291 Hz. It could withstand an overload impact of no less than 3.8×104 g, while the quality factor reached 8.7×104. The rationality, effectiveness, and accuracy of the optimization were verified by physical tests and a comparison with a -type oscillator.

When measuring the transient response of MWIR HgCdTe photovoltaic devices, the device presented a special bimodal pulse response phenomenon when the surface position of the device irradiated by the laser spot was far away from the photosensitive surface. It is analyzed that the abnormal double pulse phenomenon was due to the time difference between the drift of minority carriers in the photosensitive region and the diffusion of minority carriers collected laterally outside the photosensitive region. By applying reverse bias to the device, the impulse response changed from bimodal to unimodal with the increase of reverse bias, which verified that the lateral collection of minority carriers was the main reason for the bimodal formation of the device. The minority carrier lifetime of p-region materials was obtained by fitting the second peak. Comparing the minority carrier lifetime obtained from the transient response with that obtained by the theoretical calculation and the photoconductivity decay method of the p-type MWIR HgCdTe material, it is found that the trends of the minority carrier lifetime obtained from the three methods with temperature are basically the same, which indicates that the minority carrier lifetime of MWIR HgCdTe material can be obtained from the transient photoresponse.

Soliton optical combs in microresonators have broad application prospects in coherent optical communication, optical frequency synthesis, lidar, microwave photonics and quantum optics. Efficient prism coupling provides an inevitable technical approach for integrated application and system packaging of soliton frequency combs in crystal microresonators. In this paper, a MgF2 microresonator-prism coupling system with the coupling efficiency of 71.56% and loaded Q value of 1.8×109 was developed. Based on this efficient prism coupling system, the generation of MgF2 microresonator soliton frequency comb and the low-phase noise microwave signal of 15.99 GHz were realized. And the phase noise level of beat frequency signal is about -117 dB/Hz@10 kHz. It will promote the practical application and development of low-phase noise micro-photoelectric oscillator.

The surface absorption loss of an optical component is an important index used to measure its optical performance. The attachment of pollutant particles usually causes a significant increase in the surface absorption loss of an optical component. This study used the temperature rise detection method of an infrared thermal imager to investigate the influence of several typical pollution particles on the surface absorption loss of a highly reflective mirror. Stepped and discrete distribution absorption models were established based on the distribution characteristics of these pollutant particles. Considering that the temperature measurement accuracy was affected by the spatial resolution of the infrared thermal imager, the temperature rise data for a single pixel were extracted for a finite element analysis, and the local absorption loss on the surface of the coated element with an accuracy equivalent to that of a single pixel was obtained. Microscopy scanning results were used to further optimize the simulation model and obtain the absorption loss of particulate pollutants on the surface of a thin film element.

Shape sensing technology is a new research direction in recent years and has a wide range of application prospects. In this paper, a shape reconstruction method based on strain mode mode and error compensation is proposed. By measuring the strain data of some position points of the object, the modal theory was used to realize the strain-displacement transformation, and then the shape of the object was reconstructed. In this paper, titanium alloy plates with length, width and height of 1 000, 1 000 and 0.5 mm were taken as the research object. The displacement mode and strain mode modes were obtained by ANSYS workbench 18 finite element simulation software. According to the modal similarity of position points in the finite element simulation, the K-means++ clustering algorithm was used to optimize the position of strain measuring points, and the strain deformation was generated by applying 400 N force on the upper surface of the alloy plate. The shape reconstruction error of the proposed algorithm is smaller than that of the conventional uniform distribution algorithm. A Radial Basis Function Neural Network (RBFNN) was used to train the error and reconstructed displacement data set. According to reconstructed displacement prediction error, the fitting error was less than 3.5%.

Quartz tapered sidewall etching using a two-step etching method was studied based on photoresist modification technology. First, the vertical sidewall of the photoresist was modified to a tapered profile using Ar/O2/CF4 plasma. Then, the tapered sidewall of the photoresist was transferred to quartz using the same etching chamber. The influences of gas flow, etching power, temperature, and etching time on the etching rate, selectivity, and morphology during the photoresist modification process were studied in detail. A tapered quartz profile with a sidewall angle of 60° and a smooth surface was prepared by optimizing the process parameters. This work provides a helpful guideline for the tapered sidewall etching of SiO2, as well as other materials.

In order to meet the requirements of performance indexes of φ-OTDR in complex engineering field environment, a high-performance φ-OTDR based on adaptive Kalman filter (AKF) and frequency division multiplexing (FDM) is proposed. On the basis of improving frequency response bandwidth of FDM, AKF is used to estimate and correct the statistical characteristics of phase noise linearly responding to external vibration in real time, effectively suppressing the phase distortion caused by fading and crosstalk noise. The experimental results show that sensor linearity of the system is improved, the background noise of the system is reduced to -83.7 dB2/Hz, and the strain resolution is reduced to 0.28 pε/Hz1/2.

Flexible organic films are important functional materials with a wide range of applications in many areas such as electronic devices and packaging. However, some organic films have shortcomings such as insufficient hydrophilicity, poor biocompatibility, and low chemical reactivity. Introducing hydroxyl functional groups through surface treatments can enhance the hydrophilicity of organic films, and improve their properties and functions, making them more suitable for various application fields. This study conducted dry and wet hydroxylation treatments on the surfaces of flexible organic films to investigate the impact of hydroxylation processes on their hydrophilicity. The results indicated that when the wet hydroxylation treatment time and temperature were increased, the water contact angle on the organic film surface initially decreased and then stabilized. In contrast, when the plasma treatment time was increased, the water contact angle first decreased and then increased. Additionally, the water contact angle of a surface treated with dry hydroxylation was approximately 20° lower than that treated with wet hydroxylation, resulting in better hydrophilicity of the organic substrate and a shorter processing time.

In order to meet the requirements of vehicle photoelectric theodolite on the control precision, stability, weight and volume of the servo control system, relevant research was firstly carried out on the main power supply of the servo control system. As the energy supply unit of the servo control system, the stability of the main power supply determined the stability of the servo control system. Then the tracking precision and tracking frequency of the servo control system were affected. In this paper, the design requirements of the power supply, the main circuit, the maximum pulse width limiting circuit, PWM control circuit, voltage and current detection circuit and voltage feedback control circuit were described. At the same time, the power supply was designed according to this method, and the test results were obtained: the power output is 48 V DC; the output power is 2 400 W; the peak-to-peak value is 310 mV; the weight is 13.8 kg; the volume is 350 mm×200 mm×110 mm.

This paper proposes a metamaterial structure based on a periodic square-ring array of three-dimensional topological insulators (Bi1.5Sb0.5Te1.8Se1.2). Simulation results showed that the surface plasmon resonance intensity of the metamaterial structure was enhanced with decreases in the array period and size of the square ring, where 80% of the electromagnetic wave could be confined to the surface states when the period was 300 nm or the size was 25 nm. In addition, the circular dichroism of the metamaterial and non-metamaterial structures under the incidence of positive and oblique circularly polarized light were obtained by simulating the relationship between the variation of the surface electric field and polarization of the metamaterial and non-metamaterial structures under positive and oblique incidence. The circular dichroism of the metamaterial structure (0.92) was much larger than that of the non-metamaterial structure, and there was a significant increase in the ratio of the circularly polarized component to the total polarized component for this metamaterial structure, which was attributed to the fact that more spintronic electrons were excited by the circularly polarized light from the topological surface state to the body conduction band.

Spacecraft remainders online detection is affected by insufficient marker data. In this paper, the physical characteristics of remainders generation were studied, a remainders model in spacecraft digital twin systems was established, and a cross-domain adaptive spacecraft remainders detection method with digital twin enhancement was proposed. This method was augmented by digital twins to acquire real-time spacecraft data. It then combined similar structural historical marker data and applied a cross-domain adaptive approach to assist current online reasoning. In addition, a new type of cross-domain adaptive approach model was proposed to better mine prior knowledge from complex tasks through a shared network structure and gating mechanism. The model realizes a combination of cross-domain adaptive techniques and digital twins for more efficient, accurate and real-time prediction. This method can comprehensively detect the remainders states of different components of spacecraft.

To address the instability of the front cavity surface under high current, which can lead to catastrophic optical mirror damage (COMD), a semiconductor laser with a dual-zone electrode structure was proposed. This study investigated the COMD threshold, peak power, threshold current, spectral stability, and kink effect of this laser structure. Under the same process conditions, the COMD threshold, peak power, threshold current, and wavelength redshift rate of semiconductor lasers with a single-electrode structure and dual-zone electrode structure were tested. The results showed that, under the same process conditions, with a threshold current of 80 mA in the main gain region, the threshold current of the laser with the dual-zone electrode structure was reduced by 20%. When driven by a 15 mA current in the window region, compared to the single-electrode semiconductor laser, the semiconductor laser with the dual-zone electrodes could increase the COMD threshold by 13%, increase the peak power by 12%, and decrease the wavelength redshift while improving the kink effect.

When the star sensor is operating in space, it is easy to be interfered by stray light such as sunlight, moonlight and earth-air light. As a result, the overall gray level of the star map taken is increased, the background uniformity is poor, and it is difficult to accurately extract the star coordinates. Aiming at the above problems and combining the existing algorithms, a composite background estimation star map processing algorithm under stray light interference is proposed. First of all, star points had the characteristics of dimensions ranging from 3×3 to 7×7 in diameter after point diffusion imaging, so the corresponding background estimation template was designed. Then, in order to improve the robustness of the algorithm and the utilization rate of local information, a pixel estimation template was designed. The two estimation templates calculate the post-processing data at the same time to achieve threshold segmentation, and then the centroid of star points was calculated. This method can better resist stray light interference and improve the accuracy of star extraction under stray light background.

This article proposes a method for charge accumulation in a large-pixel CCD, which includes two aspects: The first is the subdivision of vertical and horizontal pixel structures within the device and the sum of charge packets. The second is the multiphase nonuniform driving in driving timing. This method is applied to a 210 m×210 m pixel CCD and is used to build hardware circuits and design software. Its effectiveness is verified via acquisition imaging and parameter testing. Results show that a large full-well capacity and dynamic range are achieved without compromising transfer efficiency.

As for the transmission channel in airborne laser communication, research onto combined transmission effects, including channel attenuation, intensity scintillation, beam-wandering and aero-optics effects in the atmospheric channel, were analyzed. Furthermore, transmission performances onto received beamwidth, link outage probability and bit-error rate were derived. The simulation results show that the received beamwidth is boosted by beam-wandering and aero-optics effects, and the beam size at low altitude condition is larger than the high altitude case due to severe atmospheric turbulence. On the other hand, long-range transmission links need to take into account the beam-wandering effect, which can be suppressed by optimizing transmitted laser beamwidth.

Based on the three-dimensional piezoelectric-semiconductor (PSC) and first-order shear-deformation theories, and considering the coupling extension, flexure, and shear deformations, a buckling model for a one-dimensional functionally graded PSC extension-flexure beam was established. The stability of a functionally graded PSC extension-flexure beam under an axial load was analyzed via the finite element analysis software COMSOL, and the first three critical buckling loads and distributions of the electromechanical field for a simply supported beam were obtained. The influences of the beam length-height ratio, initial electron concentration, and functionally graded parameters on the critical buckling loads are discussed based on some numerical examples.

To address the problems of low accuracy and complex computation of AKAZE (accelerated-KAZE) algorithm in image matching, an image matching algorithm based on the combination of Gaussian filtering and AKAZE-LATCH (AKAZE-Learned Arrangements of Three Patch Codes) algorithm is proposed. Firstly, the input image was preprocessed by Gaussian filtering to remove continuous noise such as Gaussian noise, and retain the edge information of the image. Then, efficient binary descriptors were constructed for AKAZE using LATCH algorithm, and corresponding matching pairs were obtained using KNN (K Nearest Neighbors) algorithm. Finally, the method was screened again with USAC (Universal RANSAC) to remove false matches, and the final matching result was obtained. Experimental comparison shows that compared with AKAZE algorithm, the proposed algorithm has higher matching accuracy, good robustness and reliability, and can be used for image matching in most complex scenes.

In this study, we implemented a 56 Gb/s NRZ and 112 Gb/s PAM-4 dual-mode transmitter design on a 28 nm CMOS process. For the equalization, we used a data multiplexing architecture to support a fully configurable segmented feed-forward equalizer (FFE). Next, we adopted a current-mode logic (CML) driver topology, with a pull-up current source, as the terminal output network. The key circuit structures and techniques included relying on a paragraph allocation module to allocate paragraphs for the FFE and achieving coarse adjustments of the tap weights. We utilized a pre-charged 1-UI pulse generator and 4∶1 MUX to enhance the bandwidth. The driver incorporated a load-side parallel current source to boost the common-mode voltage and a T-coil to extend the output bandwidth and swing. Our simulation results demonstrated that the eye heights for the 112 Gb/s PAM4 and 56 Gb/s NRZ output were 40 and 130 mV, respectively.

To address the insufficient local feature extraction and lack of context feature fusion in three-dimensional laser point clouds, we propose MAKNet, a point cloud feature extraction network that integrates a self-attention mechanism with a multi-level feature extraction architecture. Taking three-dimensional laser point cloud data as input, MAKNet employs an SAA module to extract point cloud features. It enhances sparse point recognition by introducing attention weights between the central point features and neighboring point features. Furthermore, MAKNet utilizes a multi-scale feature extraction approach to extract and fuse multi-layer point features, followed by point cloud feature skip connections to increase the coverage of the extracted point information. Experimental results demonstrated that on the S3DIS dataset, the overall accuracy of MAKNet was 86.9%, which was an improvement compared to that of PointNet++ (80.1%). On a self-built dataset of transmission line corridors, MAKNet achieved an overall accuracy of 96.4%, showcasing its robustness and strong generalization capabilities in semantic segmentation tasks.

In aerospace applications, a HgCdTe infrared detector preamplifier circuit yields the normal output at room temperature; however, it exhibits oscillations when the temperature is reduced to -55 ℃, and these oscillations intensify when infrared light is irradiated to the detector. In this study, this phenomenon is systematically investigated for the first time, and an equivalent circuit model of a HgCdTe infrared detector circuit after low-temperature irradiation is presented. The mechanism of the oscillation of the preamplifier circuit at low temperature is analyzed in terms of phase and gain margins. Based on the analysis, a solution is proposed to inhibit the oscillation of the preamplifier circuit after illumination at low temperatures. The validity of the method is confirmed experimentally.

To address the problem of low data utilization efficiency in the coarse-aiming prediction of a single-detector composite axis, a real-time prediction method based on Kalman filtering and the least-squares method is proposed and validated via simulations using actual vibration data. The results show that as the step size increases, the correlation between data points decreases, thus reducing the prediction accuracy and stability.

To precisely measure phase signals in phase-sensitive optical time-domain reflectometers, a novel noise-reduction method is proposed that is based on complementary ensemble empirical modal decomposition coupled with singular value decomposition using a permutation entropy algorithm. Initially, a phase signal containing noise is decomposed via complementary ensemble empirical modal decomposition (CEEMD) to obtain a series of components with different frequencies. Subsequently, the PE algorithm is combined with the correlation coefficient mechanism to retain useful components with a larger correlation, and the singular-value-decomposition algorithm is used to denoise the noise components with a smaller correlation. Finally, the useful components, retained after two denoising processes, are reconstructed. Simulation and experimental results demonstrate that, compared with empirical modal decomposition, ensemble empirical modal decomposition, and CEEMD, the proposed method achieves a higher signal-to-noise ratio, which is beneficial for the precise measurement of phase signals.

This paper proposes a real-time denoising algorithm for fiber optic gyroscopes based on redundant second-generation wavelet transforms. The algorithm directly utilizes predictors and updaters with zero-padding interpolation to decompose and reconstruct signals. This approach ensures that the lengths of the approximation and detail signals are the same as that of the original signal, thus preventing signal distortion after reconstruction. The results of experiments on both simulated and actual output signals from fiber optic gyroscopes demonstrated that the algorithm effectively preserved the temporal characteristics of the signals, ensuring that their integrity and accuracy were not compromised by the denoising process. Moreover, it decreased the quantization noise by approximately 50.23%, decreased angular random walking by approximately 19.14%, and mitigated bias instability by approximately 53.02%. Thus, it provides an effective method for signal processing in fiber optic gyroscopes.

A novel construction method with grith-8 quasi-cyclic low-density parity-check (QC-LDPC) codes based on the Golomb ruler is proposed to solve the issue of short-cycle structures affecting error-correction performance. First, a set is constructed by selecting some elements from the Golomb ruler based on the code-length and code-rate requirements. Subsequently, by combining the girth-4 and girth-6 properties of the elemental locations in the exponential matrix, another set is obtained using the search algorithm to search for elements that satisfy the conditions of no girth-4 and no girth-6. Subsequently, the corresponding exponential matrix is constructed. Finally, a parity-check matrix is obtained. Simulation results show that the net coding gain of the GR-QC-LDPC code constructed using the proposed method is greater than those yielded by four other QC-LDPC codes with the same code-rate and code-length at a bit error rate of 10-6; moreover, its error floor is insignificant.