To predict complex weather changes accurately and within a reasonable timeframe in practical applications, ice crystal particle cloud models were constructed using a combination of ellipsoidal hexagonal plates, ellipsoidal tetrahedra, hexagonal tetrahedral plate, and ellipsoidal hexagonal tetrahedra plate. An analytical function of the standard gamma distribution was used to approximate the spectral distribution of the ice crystal particle clouds. The extinction coefficient, absorption coefficient, and a single scattering albedo of the newly constructed cloud model were analyzed, and the effects of incident wavelength and cloud model on the function of the scattering phase were studied. We built a cold chamber to grow ice crystal particles and conducted experiments on their generation at different temperatures. We used a three-band atmospheric integral turbidity meter to measure the extinction coefficient and scattering coefficient of the newly constructed ice crystal model. Our results showed that the scattering phase functions of the four newly established models for ice crystal particle clouds exhibited peaks within the ranges of 22o‒46o and 140o‒160o, which were results similar to those of the classical MODIS6 ice crystal particle cloud scattering model. As the experimental time changes, the extinction and absorption coefficients show multiple extreme values and exhibit randomness. However, the experimental and simulation values of the four newly established models are in good agreement, which verifies the rationality of the proposed cloud model. The results also further supplement and improve the ice crystal particle cloud model, select appropriate ice crystal particles for cloud modeling, and provide support for the accurate prediction of weather changes.

An electron multiplication charge-coupled device (EMCCD) and microchannel plate (MCP) image intensifier use high-voltage electric fields to multiply electrons after photoelectric conversion and photoelectrons converted from photocathode materials, respectively. The photo-electronic amplification technology used in both devices introduces additional noise factor, resulting in a decrease of the signal-to-noise ratio (SNR). A scientific complementary metal-oxide-semiconductor (sCMOS) image sensor is a detector proposed in recent years that does not rely on external structures and achieves high sensitivity by optimizing the CMOS pixel process, pixel structure, and readout circuit noise level. This paper proposes a method of calculating the modulation transfer function (MTF) and SNR of low-light detectors based on their optical and electrical parameters. For the same number of incident photons, the SNR of sCMOS, MCP, EMCCD low-light detectors are 6.89, 3.53, and 9.67, respectively, when the integration time is 1.0 s. The comprehensive MTFs at the Nyquist frequency are 0.63, 0.13, and 0.48, respectively. The product of the SNR and MTF at the Nyquist frequency is used as the imaging quality standard to compare and analyze the theoretical characteristics and applicable fields of the three low-light detectors.

This study proposes a cascade-type fiber curvature sensor with bowknot-type taper and a tapered fiber structure based on intermodal interference. The proposed sensor comprises two bowknot-type tapers prepared by fiber fusion splicing using single-mode fibers, and the tapered structure is added by fixed-point tapering. Experimental results show that when the tapered structure has a pulling cone length of 0?2500 μm, the sensitivity of the sensor increases alongside the pulling cone length; furthermore, for pulling cone lengths of 3000 μm and 3500 μm, sensor sensitivity tends to be stable. The maximum sensitivity reaches -22.50 nm/m-1 in a curvature range of 3.4072?6.0881 m-1 for a pulling cone length of 2500 μm. This structure has both high sensitivity and high stability, which effectively solves the problem of temperature cross-sensitivity and simultaneously simplifies the sensor manufacturing process, improving its compactness and reducing the production cost.

Aiming to solve the issue of increased peak-to-average power ratio (PAPR) caused by flipping operation in a flip orthogonal frequency division multiplexing system, a dynamic clipping compensation combined with a μ-law expansion technique is proposed to suppress the PAPR of the system. First, based on the flipping characteristics, the positive and negative signals that meet the clipping criteria are clipped, and the clipped values are compensated at the zero signal positions of the corresponding index's negative and positive signals. Then, the cropped signal is subjected to a μ-law compression-expansion transformation to increase the average power of the signal. Finally, at the receiving end, the clipped and compensated signals are compared using maximum likelihood. The preclipped signal is restored based on the compensated signal, and the compensated signal is then set to zero to reduce signal distortion. The simulation results show that under the conditions of pulse amplitude modulation, complementary cumulative distribution function of 10-3, and no loss in bit error rate, compared with the flipping system and the μ-law algorithm, the proposed algorithm reduces PAPR by 6.01 dB and 2.81 dB, respectively.

Distributed optical fiber sensing technology can obtain the parameters of strain, temperature, and vibration along the sensing direction of a structure, and it is especially suitable for linear engineering monitoring. In this study, the failure condition of pipeline structure is determined by multi-parameter monitoring of strain, temperature, and vibration in a pipeline, and the applicability of sensing each parameter in judging pipeline structure failure is analyzed. The test results show that pipeline damage under different conditions can be identified by strain, temperature, and vibration sensing. There is soil falling in the damaged area, which results in local negative strain of the pipeline. Under active heating conditions, when the pipeline is full of water, the temperature of the optical cable in the damaged area is higher than that in other areas, and when the pipeline is not filled with water, the temperature of the optical cable in the damaged area is lower than that in other areas. The peak vibration frequency of the optical cable in the damaged area of the pipeline is offset from that in other areas. Strain, temperature, and vibration signal sensing can be used to locate the pipeline failure area accurately, with a positioning accuracy of ±1 cm, and a reasonable combination of sensing parameters can aid in monitoring actual pipeline structure failure precisely. These results provide a reference for the application of distributed optical fiber technology in the structural health monitoring of urban buried water pipelines, and this technology has a good development prospect.

With the increasing global demand for high-speed satellite communication, 100 Gb/s intersatellite coherent optical communication technology is becoming the main solution for efficient intersatellite data transmission. The application of coherent optical communication significantly improves the data transmission rate, can satisfy the requirements for large-capacity data transmission, and is suitable for communication between low Earth orbit. Intersatellite coherent optical communication technology, combined with digital signal processing (DSP) algorithm, reduces bit error rate (BER) and ensures reliable transmission via effective channel equalization and signal demodulation. In this study, high order modulation scheme combined with DSP is used to verify 100 Gb/s link transmission performance, and the influence of satellite pointing error and inter-satellite distance on transmission performance is analyzed. The simulation results show that quadrature phase shift keying (QPSK) exhibits stronger robustness to satellite pointing error and inter-satellite distance than 16 quadrature amplitude modulation (16-QAM) signal under 100 Gb/s transmission. At a BER of 3.8×10-3, the pointing error and intersatellite distance tolerance of QPSK are 1.3 and 1.8 times those of 16-QAM signal, respectively. The spectrum efficiency of 16-QAM signal is higher, which can reduce the requirements of bandwidth and sampling rate of photoelectric devices. Therefore, in a future 100 Gb/s inter-satellite coherent optical communication system, the device bandwidth and satellite dynamic characteristics can be comprehensively considered to complete the system design.

A high-sensitivity optical fiber Fabry-Perot (F-P) temperature sensor based on the harmonic vernier effect (HVE) is proposed and fabricated to achieve high-sensitivity temperature measurements. The sensor consists of two parallel F-P interferometers formed by single-mode fiber (SMF)-air-SMF and SMF-polydimethylsiloxane (PDMS)-SMF, where the air cavity serves as the reference cavity and the PDMS cavity serves as the sensing cavity. By changing the length of the reference cavity and paralleling it with a sensing cavity of the same length, sensors 1 and 2 are fabricated for temperature-sensing experiments based on the traditional vernier effect (TVE) and HVE, respectively. Experimental results show that within the temperature range of 31?35 °C, the temperature sensitivity of a single sensing cavity is 1.640 nm/°C. The temperature sensitivities of sensor 1 based on TVE and sensor 2 based on HVE reach -5.125 nm/°C and 16.025 nm/°C, respectively, which are 3.12 and 9.77 times of that of a single sensing cavity. Compared with single and TVE sensors, the HVE sensor can achieve higher temperature sensitivity. Moreover, the sensor is easy to fabricate and can satisfy different temperature requirements, which thereby exhibits broader application prospects.

The measurement system was designed that utilizes the principle of photoelectric autocollimation to detect the dynamic pitch misalignment angle of a precision centrifuge. The system allows for real-time measurement of pitch angle variations at the end of the centrifuge arm, situated outside the centrifuge chamber. An external trigger module determines when the centrifuge reaches the measurement position and generates a trigger signal to initiate the measurement process. Experimental analyses were conducted to evaluate the signal-to-noise ratio of the detector under varying exposure levels, and an automatic dimming module was implemented to mitigate inconsistencies in image gray levels at different centrifuge speeds. Simulation experiments were conducted to analyze measurement errors in the optical path and the effects of environmental temperature fluctuations. Finally, on-site measurements of the dynamic pitch angle were performed at the centrifuge facility, achieving a measurement repeatability of 0.207″.

Diffraction optical waveguides have the advantages of compact size and light weight for augmented reality displays. The period of subwavelength gratings on the surface of grating waveguides significantly affects imaging quality, making it essential to achieve fast and accurate measurements of grating periods. The Littrow diffraction method has the advantages of low cost and non-destructive properties. However, it requires precise alignment of the grating sample, necessitating multiple adjustments prior to measurement, which hampers rapid evaluation. To address this problem, this study analyzes the diffraction characteristics of misaligned gratings and proposes an image processing-based method to calculate the misalignment angle and correct measurement errors. The proposed method enables accurate measurement of the grating period under conditions in which the grating pose is not strictly aligned, thereby enhancing measurement efficiency, it is expected to achieve facilitating rapid detection of augmented reality grating waveguides.

The focal length, curvature radius, and refractive index of a lens are important parameters that characterize the lens’ performance and are essential for selecting lenses in optical design. This study proposes a lens parameter measurement method based on the Shack-Hartmann wavefront sensor (SHS). First, the reference point for measuring the focal length of the lens under test is determined by evaluating a function that calculates the sum of the least squares of the centroid offsets of the light spots formed by the SHS (LSSCS). The focal length of the lens can then be obtained by measuring the curvature radii of two spherical waves at two different distances from the reference point. The curvature radius of the lens surface is then calculated by determining the coordinate difference between two specific positions. These positions correspond to the points at which the reflected light beam on the lens surface becomes parallel to the incident beam, as determined by the LSSCS evaluation function. Finally, for thin lenses, the refractive index of the tested lens material is calculated using the lens manufacturer’s formula based on the measured focal length and surface curvature radius. The experimental results demonstrate that the lens parameters measured by the proposed method are in excellent agreement with the nominal values. The proposed method offers several advantages, including simplicity, accuracy, and resistance to interference, while eliminating the need for wavefront reconstruction.

The lack of mature detection methods for the high-precision measurement of chip warpage during thermal cycling affects the optimization of chip performance and improvement of packaging processes. To address this issue, we design and develop a three-dimensional (3D) detection system based on monocular fringe structured light, combined with infrared temperature detection. This study focuses on 3D reconstruction and warpage calculation methods for chip surfaces under varying thermal environments. By integrating fringe Gray code and the phase-shifting method, high-precision 3D reconstruction of point cloud data on chip surfaces is achieved. Additionally, the Robust Gaussian Lowess fitting algorithm is applied to fit the surface of point cloud data, reducing the fluctuation caused by noise points by approximately 30%, enabling accurate warpage calculation for chips. Experimental results demonstrate that the proposed method effectively suppresses noise and outlier effects in point cloud data, significantly improving the robustness and accuracy of surface fitting. It shows particularly high stability under thermal cycling conditions. The optical measurement system designed in this study is validated to meet micron-level warpage measurement requirements, providing reliable technical support for chip design and packaging process optimization. The system exhibits excellent application potential in complex thermal cycling test scenarios and offers a new solution for the high-precision quality detection and control of electronic components.

The modulation asymmetry of a multifunction integrated optic circuit (MIOC) can be characterized by the difference in the phase response to modulation electric fields with the same magnitude but different directions. The X-direction vertical component of the modulated electric field is one of the main reasons for the phase difference in this modulation. The difference in modulation phase during equal amplitude reverse modulation of the modulator introduces nonlinear phase errors in the fiber optic gyroscope optical path, which are difficult to directly suppress using phase compensation. This article proposes a sinking-electrode design for suppressing modulation asymmetry in modulators, which simultaneously improves the modulation efficiency of the modulator and significantly reduces the half-wave voltage of the modulator. By establishing a finite element simulation model, electrode parameters that meet application requirements were designed, the manufacturing process tolerance of the sinking-electrode modulator was analyzed, and etching experiments were conducted for verification. Compared with traditional modulators, modulators based on sinking electrodes have reduced the phase error of equal amplitude reverse modulation from 5×10-4 rad to 1×10-6 rad, and the maximum half-wave voltage can be reduced by 18%. The modulation symmetry and efficiency of the modulator are greatly improved, which is conducive to the development of high-performance fiber optic gyroscopes.

This study investigated the effects of heat treatment-free high-pressure die-casting Al-Si alloy weld porosity distribution and differences in microstructure characteristics on the mechanical properties of welded joints under cold metal transfer welding (CMT) and laser welding processes with the aim of enhancing the proportion of high-pressure die-casting aluminum alloy used in automotive structural parts. The results show that under the effect of beam oscillation, the porosity of the laser weld is as low as 1.5%, which is 80% lower than that of the CMT weld. In addition, the faster cooling rate reduces the secondary dendrite arm spacing of the laser weld to 2.8 μm, which is approximately 29.2% that of the CMT weld. The significant reduction in porosity and dendrite spacing results in a synergistic enhancement of the weld's strength and plasticity. Compared with CMT welds, the tensile strength and elongation after break of laser welds increased by 16.4% and 110%, respectively, due to the reduction of weld porosity and secondary dendrite arm spacing, thereby realizing a synergistic enhancement of the strength and plasticity of the welded joints of high-pressure die-casting Al-Si alloys.

Manipulating droplets composed of nonpolar solvents or bubbles in aqueous media is crucial in materials science and industrial production. In this study, a dual-circular track microdevice is prepared on an aluminum substrate surface using a nanosecond laser as a gas storage system. When the bubbles are injected onto the smaller circular, they diffuse toward the boundaries until a Laplace pressure is generated. The generated Laplace pressure, as the main driving force, can transport the bubbles along the trajectory toward the opposite circular point, thereby achieving a stable state when the bubbles from both circles match. Additionally, the effects of various parameters of the dual-circular track on the efficiency of bubble transportation are investigated. By altering the track width and length, as well as the diameter of two circles, fixed and unidirectional transportations of bubbles can be achieved. Based on the characteristics of the dual-circular track microdevice, complex bubble transportation trajectories are designed. These trajectories significantly benefit microfluidic manipulation, such as drug delivery, gas catalysis, and bubble accumulation.

This study investigates a compact, high-power, large-core crystal waveguide mode-locked laser. The structure of a Herriott-type multipass cavity is investigated and experiments are conducted using a high-power crystal waveguide mode-locked laser featuring a multipass cavity. The experiment achieves continuous mode-locked pulses with an average power of 33 W, a pulse duration of 3.32 ps, a repetition rate of 61.3 MHz, and a central wavelength of 1031.3 nm. The experiment simplifies the structure of the crystal waveguide mode-locked laser and reduces its volume.

Combining numerical simulation and experimental verification, we investigate the effect of the laser shot peening process on forming coordination of the perforated plates to solve the poor single-curvature forming quality of the plates with perforated structures. First, the dynamic stress evolution and residual stress distribution of laser-induced stress waves near the perforated structures under different scanning strategies are analyzed. Then, the forming ability of perforated plates and the consistency of forming curvatures between different parts of the perforated structures are explored. Results indicate that after the stress waves touch the circular perforation, the attenuation speed slows down, and the waveform slides and propagates along both sides of the half arc, and bypasses the half arc, forming an alternating tensile/compressive stress wave at the center of the half arc that penetrates the entire thickness along the depth direction. In the stripe strategy, multiple times of small energy laser shot peening enhance the stress amplitude and forming ability of the discontinuous perforation and have a gain effect on the forming coordination of the perforated plates. Under the wraparound strategy, continuous scanning of the inner and outer perimeters of the perforation decreases the negative effects caused by the discontinuous perforated structures. Additionally, the continuous stress propagation and uniform stress distribution improve the forming ability and coordination of the perforated plates. Compared with the specimens treated by stripe strategy, the forming ability of specimens treated by the wraparound strategy under the same energy is increased by 74.16%, and the deviation rate of the curvature radius in the sub-region is decreased to 3.99%.

The design and fabrication of a InP/InGaAs modified uni-traveling carrier photodetector array heterogeneously integrated on the thin-film lithium niobate platform was proposed and fabricated. The 1×N multimode interferometers were employed to ensure uniform distribution of input optical power to each photodetector unit. Experimental results demonstrate that the 1×2, 1×3, and 1×4 photodetector arrays achieve 3 dB bandwidths of 50 GHz, 45 GHz, and 40 GHz, respectively. The device was applied in an intensity modulation direct detection system, successfully achieving high-quality reception of 60 Gbaud and 100 Gbaud four-level pulse amplitude modulation signals.

Strontium titanate (STO) exhibits favorable thermoelectric properties and significant potential for application in temperature sensing. Herein, we propose a terahertz metamaterial temperature sensor based on amorphous STO combined with graphene, where the dielectric constant can be adjusted by changing the temperature of the STO film. Based on this property, the temperature sensor can be used for temperature sensing in the range from 300 to 620 K. The temperature sensor is characterized by a blue shift of the terahertz absorption peak as the temperature increases. The blue shift of the terahertz absorption peaks with increasing temperature confirms its temperature-sensing capability, and the terahertz temperature sensor has a high sensitivity of 0.51 GHz/K. To investigate the sensor's performance in a multidimensional manner, a graphene thin film is transferred to the surface of the temperature sensor via wet transfer. Results show that the combination of STO and graphene thin film improves the performance of the sensor compared with the previous method. Specifically, the amplitude of the sensor improves significantly. This study not only provides a new scenario for the application of amorphous STO in temperature sensors but also offers a new possibility for the design of easy-to-process, low-cost, high-performance amorphous STO terahertz devices.

Using a 370 nm ultraviolet GaN chip as the excitation light source, white light-emitting diodes (WLED) with a double-layer structure were prepared using blue-green carbon quantum dots/non stoichiometric thiol-ene (CQD/OSTE) and red CdSe/ZnS QD/OSTE composite materials as fluorescence conversion media. When the mass ratio of CQD to OSTE is 1∶6.1, by changing the mass ratio of CdSe/ZnS QD and OSTE composite materials, the color rendering index (CRI) and correlated color temperature (CCT) can be adjusted between 82.3-92.6 and 4231-5478 K, respectively. When the CdSe/ZnS QD: OSTE ratio is 1∶5.4, the CRI of the WLED device can reach 92.6 and the CCT is 5098 K. The prepared WLED devices exhibit good stability under 8 hours of ultraviolet irradiation. This type of WLED device with high color rendering index and stability is expected to be applied in the fields of white light illumination and display.

In recent years, perovskite-based solar cells have demonstrated outstanding performance in terms of efficiency, attracting significant attention from researchers. However, the fabrication process of perovskite solar cells typically relies on traditional trial-and-error methods to optimize process parameters, which is a time-consuming and inefficient process. To address this issue, this paper proposes a machine learning-based strategy for optimizing process parameters, using random forest, extreme gradient boosting, and adaptive boosting algorithms as base learners. A perovskite solar cell efficiency prediction model (PCEPM) was constructed using a weighted averaging ensemble strategy to predict the efficiency of perovskite solar cells for different process parameters. Experimental results demonstrated that PCEPM performance was excellent in predicting perovskite solar cell efficiency with root mean-squared error of 0.620, mean absolute error of 0.469, and R2 of 0.838. Furthermore, by predicting randomly generated process parameters and selecting the optimal ones for experimental validation, perovskite solar cells were successfully fabricated with an efficiency of 23.72%, which is a significant improvement in research and development. This approach effectively uncovers the relationships between process parameters, reduces optimization time, and provides a new perspective for the application of machine learning in perovskite materials development.

Abdominal fluorescence endoscopy significantly enhances the recognition effect of lesion tissue contours in minimally invasive surgery. However, most intra-abdominal endoscopic optical systems are designed with lens materials that consider only visible light transmission and imaging. Additionally, the existing laparoscopes are designed for adult surgery, typically exceeding 5 mm in diameter, with few options for small-diameter laparoscopes. To address this issue, this paper presents the design of an optical system for a small-diameter intraperitoneal fluorescence endoscope. The material selection considers the optical transmission characteristics of the visible and fluorescent bands. The designed system has an entrance pupil diameter of 0.1 mm, a diameter of 3 mm, a distortion of less than 22.7%, and a full field of view of 90°. At an object distance of 10 mm, the proposed system achieves center resolutions of 14 and 9.9 lp/mm for visible light and near-infrared fluorescence, respectively. The tolerance analysis results indicate that the designed system meets the actual usage requirements.

An optical-transmission head-mounted display system offers several advantages, including hands-free operation, continuous functionality under diverse conditions, and 24/7 usability, making it suitable for diverse applications. This study presents a head-mounted display device that uses a free-form prism optical transmissive display method and integrates multispectral sensors within an embedded architecture. We developed an optical display module with a large field of view, high resolution, exceptional light efficiency, low power consumption, and visual adaptability. This was achieved using a domestically manufactured Rockchip 3399 platform and a robust R&D architecture. By optimizing the multispectral sensor quality and parameters, we developed infrared, low-light, and visible-light sensors, along with MicroOLED drivers for the microimage source, resulting in a fully integrated system. Based on the native system, we developed an application that enables seamless switching between multispectral images, thereby achieving an integrated multispectral image display. As a next-generation wearable computing terminal with a high degree of localization, the proposed system demonstrates great promise for applications in park security, industrial inspection, epidemic prevention, temperature monitoring, and multidimensional perception.

Space telescopes are lightweight and have low absolute stiffness. Hence, deformations occur during ground-based testing under gravity. Once in orbit, with the release of gravity, the adjusted structures experience rebound, which significantly affects their imaging quality. Therefore, gravity unloading is essential during testing. This study investigates the deformation trends of off-axis telescopes under gravity, analyzes various unloading methods, and determines the unloading force via the position closed-loop method. The layout of unloading points is optimized based on local stress conditions, and a small-scale, easily adjustable constant-force universal unloading device is designed without interfaces. After unloading, the maximum displacement difference between the primary and secondary mirrors decreases from 44.2 μm to 4.6 μm, constituting a reduction of 90% compared with that before unloading. The maximum angular difference decreases from 9.5'' to 2.2'', constituting a reduction of 77% compared with that before unloading. The root mean square value of the wavefront aberration of the primary and secondary mirrors decreases from 0.185λ to 0.0292λ, constituting a reduction of 84% compared with that before unloading. The contact surface between the device and telescope is optimized by reducing the local maximum pressure from 49.8 kPa to 30.0 kPa, constituting a decrease of 40%. This unloading method satisfies the requirement of maintaining the relative position stability between the primary and secondary mirrors before and after gravity release.

Aiming at issues such as blade ablation, carbon deposition, and damage in critical components of aviation engines, including compressors, combustion chambers, and turbines, which result in pits, cracks, and other defects, a long working distance, small-diameter binocular measurement borescope is designed to measure these damages based on the principle of binocular stereoscopic measurement to determine the specific extent of pits, cracks, and other damages on the blades to guide repair processes. The designed borescope consists of an objective lens, an image-inverting rod lens group, and a dual-telecentric single-pass posterior objective lens that images onto two areas of 2/3 inch in image sensor. This borescope features a long working length and a small diameter, making it suitable for aviation engines, such as the CFM56 series. Considering manufacturing and assembly tolerances, the borescope meets the requirements after thermal stabilization and tolerance analysis. The optical system has a length of 570 mm and full field of view of 72°. At a measurement distance of 40 mm, the object side resolution is 6.33 lp/mm, angular resolution is 4.59 cycle/(°), and modulation transfer function exceeds 0.35@50 lp/mm, approaching the diffraction limit. The telecentricity is not more than 0.8°, single optical path diameter is not more than 2.8 mm, and overall diameter is not more than 8 mm.

To correct the wavefront combining error caused by piston, tilt, and defocus errors, an electrowetting-based liquid lens array is designed. The Comsol and Zemax software packages are employed to simulate the evolution of liquid-liquid interface in the liquid lens, driven by the working voltage. The wavefront correction ability of the liquid lens array for piston, tilt, and curvature errors under different arrangements and element spacings is analyzed. The simulation results indicate that the liquid lens array successfully corrects and compensates for wavefront aberration. The peak-to-valley value of the output wavefront, corrected by the regular hexagonal-shaped arranging liquid lens array, decreased from 45.6864 λ to 0.0340 λ; the root mean square value was reduced from 14.9127 λ to 0.0073 λ, while the Strehl ratio improved from 0.003 to 0.998. The results show that the electrowetting-based liquid lens array has considerable prospects in wavefront correction of adaptive optics field.

Tip-tilt mirror (TTM) is an important device used to maintain beam stability and eliminate wavefront tilt aberration, in order to achieve more accurate and stable control of the TTM, it is necessary to obtain a more accurate model of the TTM. In this study, the model identification and error rejection bandwidth of the TTM are measured with voice coil actuator TTM and imaging camera. First, the model of the TTM and the identification method based on pseudo-random response-impulse response estimation are introduced. Then, the timing sequence using the camera as the position sensor output and the results of the identification experiment are analyzed. The experimental results show that the identification results can better match the experimental data. After obtaining the identification model, the error rejection capability of the TTM beam stabilization system is tested under different frequency disturbance and the error rejection bandwidth of the system is 48 Hz.

A metasurface is an artificially designed two-dimensional planar structure that requires a significant amount of time to simulate using software when designing its structure. To address this issue, we propose a residual network model incorporating a mixed-domain attention mechanism for predicting the transmittance spectra of the metasurface. To construct the residual network model, various gold metasurface structure datasets are constructed and then preprocessed. Experimental results show that the transmission spectra predicted by the model are consistent with the simulation results, with an average absolute error of 0.0069 on the test set and a prediction accuracy exceeding 98.7%. Compared with other deep-learning models, the model offers significantly higher levels of prediction accuracy and efficiency, thus demonstrating its potential for the rapid design optimization of metasurfaces.

To mitigate new energy fluctuations, the joint optimization and scheduling of different units as a unified generating system is generally applied. In this study, to address the impact of uncertainties on scheduling plans, research on optimizing scheduling of new energy under uncertain conditions is necessary. In this point of view, this study proposes a distributionally robust optimization method based on Wasserstein distance to tackle the uncertainty in photovoltaic outputs. The proposed methodology first constructs an uncertainty set based on the historical output data of photovoltaic power plants, and converts the original model into a mixed-integer linear model easy to solve by using the duality theory and Karush-Kuhn-Tucher (KKT) conditions. The converted model is then solved by using column-and-constraint generation (CCG) algorithm. Finally, numerical experiments on a comprehensive system comprising multiple units to compare the optimization results of the deterministic model, the robust optimization model and the distributionally robust optimization model are given, demonstrating the effectiveness and the superiority of the proposed distributionally robust optimization model.

The propagation and dynamical characteristics of flat-topped vortex beams under different polarization states are analyzed using ABCD matrix, the generalized Huygens-Fresnel principle, and canonical momentum theory. The distributions of dynamic parameters such as energy, momentum, spin angular momentum, and orbital angular momentum during the propagation process of the beam are simulated and analyzed. It is found that when the topological charge is equal to zero, the energy flux density of the left-handed and right-handed circularly polarized beams rotates in opposite directions, and the direction of the energy flux density of the cylindrical vector beam is circularly symmetrical and divergent outward. When the topological charge is not equal to zero, the energy flux density of the light field does not change due to the change of polarization state. The spin angular momentum is an independent dynamic property of the electromagnetic field, which is related to the polarization state of the beam. When the topological charges are reversed, the spin angular momentum density distribution of the circularly polarized beam is the same, and the spin angular momentum density distribution of the cylindrical vector beam is opposite. The momentum and orbital angular momentum are proportional to the local gradient of the electromagnetic field and do not change with the change of polarization state, but are only affected by the topological charge.

During the deployment of quantum key distributed optical networks, limited quantum key resources, uneven distribution of network resources, and chaotic scheduling can result in large-scale business congestion and seriously impact optical network security. To overcome this issue, a quantum key resource allocation scheme is proposed. First, a linear programming constraint model of minimum wavelength and time slot consumption is constructed to reduce resource allocation. Second, considering the security requirements of a business, a key resource allocation method based on business priorities is proposed, combined with a dynamic key update mechanism and flexible security level adjustment strategy. Finally, a routing, wavelength, and time slot allocation algorithm is proposed, using resource evaluation values as routing evaluation indicators to identify paths with adequate resources and fewer hops while enhancing time slot utilization by establishing dynamic threshold values. The simulation results reveal that the proposed scheme can efficiently and uniformly use the resources in the network. Compared with the NPFSL-RWTA and SSL-RWTA algorithms, the success rate of optical path connection requests in the NSFNET (UBN24) network is increased by 7.9% and 16.3% (4.8% and 20.9%), respectively, considerably reducing the occurrence of business congestion and improving the optical network security.

This paper proposes a logarithmically responsive pixel structure based on a charge compensation technique. The structure retains a high-conversion-gain (HCG) node while introducing a PN junction at the low conversion gain (LCG) node. Under very high light intensity conditions, a large amount of overflow charge makes the LCG node voltage decrease continuously, which results in this PN junction gradually transitioning from reverse bias to forward bias. Moreover, the forward bias current compensates for the photogenerated current by extracting electrons, which moves the pixel from the linear phase to the logarithmic phase and extends the dynamic range. Simulation results demonstrate a linear dynamic range of 97.76 dB and a logarithmic dynamic range of 55.14 dB for the pixels, thus achieving a combined dynamic range of 152.90 dB.

Coherent LiDAR systems face challenges in long-distance target detection due to weak echo signal energy and interference from external factors such as atmospheric turbulence, resulting in low signal-to-noise ratios (SNRs) and reduced detection performance. To address these issues, we propose a joint temporal and spatial enhancement technique based on a coherent radar system with multiaperture reception to optimize the extraction of weak signals. The proposed technique improves the SNR and detection performance by extending the accumulation period in the temporal dimension and increasing the number of receiving apertures in the spatial dimension. The theoretical simulations and experimental results demonstrate the effectiveness of the proposed method. Specifically, temporal and spatial accumulation methods yield SNR gains that are consistent with the theoretical predictions. For varying accumulation times of single-aperture echo signals and equivalent accumulation times of multiaperture echo signals, the expected improvements are achieved. By combining spatial and temporal accumulation, weak echo signals with power as low as 0.56 fW are detected under conditions involving 36-aperture spatial accumulation and 20-ms temporal accumulation, achieving an SNR of 24.3 dB. The proposed technique significantly enhances the capability of coherent LiDAR systems to detect weak signals and thus holds important practical application value.

Nanophotonics plays a crucial role in modern optics. By leveraging nanostructures, the phase, polarization state, propagation direction, and frequency of light can be controlled precisely, enabling an unprecedented level of manipulation over light fields. Developments in this field have injected new vitality into the field of free-electron radiation. Combined with nanostructures, the momentum of free-electron radiation modes and the radiation frequency can be effectively manipulated, leading to the realization of coherent light sources from spontaneous or stimulated radiation, with frequency coverage extending from the THz to X-ray bands. The convergence of nanophotonics and free-electron radiation is expected to provide theoretical support for the next generation of on-chip integrated free-electron light sources, with important applications in particle detection, particle acceleration, biosensing, etc. This review begins with the fundamental principles of free-electron radiation, explores recent research on radiation generated through interactions between free electrons and photon quasiparticles, and outlines potential future directions in this evolving field.

Wire-feeding laser metal deposition additive manufacturing technology offers significant advantages over other titanium alloy forming processes. Specifically, it enables the production of complex components with high dimensional accuracy and excellent overall performance while addressing the issues of high cost, low material utilization, and inefficiency associated with traditional titanium alloy additive manufacturing techniques. Currently, wire-feeding laser metal deposition technology is transitioning from laboratory research to engineering application. A key development direction involves overcoming existing challenges by establishing an integrated theory that encompasses material, process, structure, and performance design. Researchers worldwide have conducted extensive exploratory work in this field. This review summarizes the fundamental principles and classifications of wire-feeding laser metal deposition technology for titanium alloys. It discusses advancements in the microstructure, properties, and control methods of this technology and outlines future research objectives and developmental trends.

With the advancement of glass technology in recent years, glass has become one of the most important engineering materials for applications in architecture, medicine, automotive manufacturing, flat panel displays, and electronics. Achieving the desired shape and size of glass requires precise and accurate cutting techniques. Compared to traditional glass cutting methods, laser technology offers several advantages, including superior quality, high surface finish, and rapid operational speed. This paper reviews existing glass cutting technologies, with a particular focus on the various laser cutting techniques and their current research status. Additionally, their advantages and disadvantages are compared, highlighting their limitations, which will provide valuable insights for future research and development.

In recent years, research on high-energy, high-repetition-rate pulsed laser systems has made significant progress and demonstrated broad application potential. Focusing on the cooling mode of laser amplifiers, this study investigates key thermal management technologies for high-energy, high-repetition-rate pulsed laser amplifiers from three perspectives: the selection of gain medium, cooling mode, and cooling configuration. This study summarizes both domestic and international advancements in thermal management technologies, analyzes the main challenges in current thermal management practices, and forecasts the future development trends of these technologies.

Optical nonlinear effects refer to phenomena wherein the response of materials to light changes nonlinearly with increasing light intensity. With advancements in laser technology, the increasing intensity of light causes pronounced nonlinear effects in optical system components. Optical thin films are optical components comprising stacked materials with high and low refractive indices. They are crucial in modern optical systems because of their regulatory flexibility, ease of manufacturing, and integration. Therefore, the nonlinear effects in optical thin films have emerged as a notable research area. This article reviews and discusses the physical mechanisms, measurement techniques, control strategies, and applications of the Kerr, nonlinear absorption, and third harmonic effects in optical thin films. It also highlights prospects for further research on third-order nonlinear effects in these films.

Laser communication is regarded as the development direction of the new generation communication technology due to its advantages of high transmission rate and large communication capacity. It is expected to play an important role in the sixth-generation communication technology, and building inter satellite laser communication links has become one of the research focuses of satellite networks. This article first introduces the advantages of inter satellite laser communication links compared to traditional satellite networks. It elaborates on the research hotspots and development status of capture technology, communication transmission technology, and inter satellite routing technology from the architecture construction of inter satellite laser communication. It also introduces the existing technology methods for integrating laser and RF communication. Finally, it looks forward to the future development of inter satellite laser communication.

High-power linearly polarized fiber laser has important applications in coherent combination, nonlinear frequency transformation, and gravitational wave detection, and becomes one of the research hotspots in the field of fiber laser in recent years. As the output power scales, thermal effects result in polarization coupling and the increase of high-order modes (HOMs), which will lead to the instability of the output laser polarization state and reduce the polarization extinction ratio (PER) of output laser. This study summarizes the polarization control of high-power linearly polarized fiber lasers, systematically expounds the limiting factors in polarization control and power enhancement of fiber laser, introduces the progress of the corresponding polarization control techniques in detail, and summarizes the typical research results at home and abroad in recent years.

The future of electronic warfare, radar, wireless communication, and other advanced electronic systems is trending towards high-frequency band, large bandwidth, wide dynamic range, and integrated multifunctionality. As the operational frequency bands expand and instantaneous bandwidths increase, the instantaneous reception of ultra-wideband radio-frequency (RF) signals has become a challenge. Microwave photonics-based channelized receiving technology, with advantages of large bandwidth, parallel processing capability, and electromagnetic interference resistance, is an enabling technology for the instantaneous reception of ultra-wideband RF signals. This article provides a systematic review of the latest research progress in microwave photonics channelized receiving technology. First, it summarizes and analyzes the working principles and technical characteristics of various microwave photonics channelized receiving techniques. Then, it discusses the image reject technology and self-interference cancellation techniques in the superheterodyne architecture of channelized receivers. Finally, it looks forward to the future development trends of microwave photonics channelized receivers.

The mid-infrared 3?5 μm laser band is located in the atmospheric transmission window and holds highly significant applications in various fields, including environmental monitoring and laser medicine. Combined with nonlinear effects of crystals, generating a mid-infrared laser based on both optical parametric oscillation and optical parametric amplification possesses advantages including high power, large energy, and wide tuning range, which can also facilitate the miniaturization and integration of laser systems by optimizing their pump sources. Among numerous nonlinear crystals, ZnGeP2 (ZGP) is the preferred crystal for mid-infrared lasers owing to its large nonlinear coefficient, high damage threshold, and other advantages. This study focuses on mid-infrared ZGP lasers based on optical parametric oscillation and optical parametric amplification, by summarizing the latest research advancements in this field, analyzes and summarizes the existing issues with the current technology, and provides an outlook on directions for future development.

Organic solar cells involve processes such as the generation, separation, and transmission of photogenerated charges, which directly affect their efficiency and stability. Femtosecond transient absorption spectroscopy (fs-TAS) is an effective technique for understanding the dynamics of photogenerated electron transfer. By measuring the response to femtosecond laser pulses, fs-TAS provides deep insights into the photoexcitation and energy transfer mechanisms in optoelectronic materials, helping optimize material performance. This review summarizes research on femtosecond time-resolved absorption spectroscopy in organic solar cells and contributes to the understanding of this research field both domestically and internationally. It comprehensively introduces the working principles, hardware equipment, and data processing of fs-TAS and two-dimensional electronic spectroscopy, followed by discussing their application progress in the photogenerated charge dynamics process of organic solar cells. Finally, future developments in organic solar cells are discussed. This review aims to serve as a reference for peer researchers in femtosecond time-resolved absorption spectroscopy.

Knife is one of the common types of physical evidence at crime scenes. Thus, establishing an accurate method for identifying them is of great significance. 138 types of common knives are collected from the market, including 57 types of fruit knives and 81 types of blades. Each sample is tested three times using an X-ray fluorescence (XRF) spectrometer, resulting in 414 sets of data. Additionally, each sample is tested 10 times using a laser-induced breakdown spectroscopy (LIBS) instrument, yielding 1380 sets of training data, and an additional 2 times, generating 276 sets of prediction data. After preprocessing the XRF data and screening for characteristic elements, three characteristic elements, Fe, Cr, and Mn, with high content and stable detection values are selected to roughly classify the samples into five subcategories. After preprocessing and feature extraction of the LIBS data, the training and prediction data are divided into five sub-training sets and five sub-prediction sets, according to the five subcategories. These five sub-training sets are used simultaneously to train five RF sub-models, and five sub-prediction sets are used for prediction. The total prediction accuracy of the five RF sub-models is used as the final prediction accuracy. Finally, these results are compared with those of the RF model trained and predicted using the total training set and total prediction set, and the advantages of combining with XRF technology are analyzed. The study shows that using XRF data for rough classification can improve the recognition accuracy of the subsequent LIBS combined with RF model, and the improvement is more significant when the training data are less.

Spectrometers have important applications in scientific research, industrial production, and daily life. Traditional dispersive spectroscopy spectrometers often have a large volume while achieving high-resolution measurements. In recent years, computational reconstruction spectrometers based on single speckle images have attracted much attention due to their advantages of high resolution and compactness. However, this scheme requires iterative optimization during spectral reconstruction to improve measurement accuracy, so the time cost is generally on the order of minutes, which limits its real-time application. This article introduces the automatic differential optimization algorithm into the speckle calculation spectrometer, which significantly reduces the spectral reconstruction time from the minute level to the second level without affecting the measurement accuracy. It achieves spectral measurement with a resolution of 2 pm and over 2000 channels, providing a new solution for rapid calculation and measurement of speckle based spectra.