The subaperture stitching method based on computer-generated holograms (CGH) is a common approach for measuring the surface profile of cylindrical mirrors. However, the stitching result suffers from distortion in low-frequency surface shape information. This is primarily caused by the cumulative amplification of errors and the inability of conventional aberration fitting methods (based on orthogonal polynomials) to effectively separate errors from the true surface figure. To address this issue, this paper proposes a novel method to compensate for and correct the low-frequency information of cylindrical mirror surface profiles. First, an initial stitching is performed using a successive subaperture stitching method based on Chebyshev polynomials. Next, the profile along the mirror's stitching direction (i.e., the generatrix direction) is measured independently to extract its low-frequency component. Finally, this low-frequency information is used to further fuse and correct the initial stitching result. Experimental validation was conducted on a cylindrical mirror with a clear aperture of 150 mm × 210 mm and a radius of curvature of 790.23 mm. The results demonstrate that the proposed method effectively corrects the generatrix direction profile of the cylindrical mirror. Compared to the full-aperture reference surface obtained via full-aperture CGH measurement, the root mean square (RMS) of the residual error for the stitching result is approximately 0.0103λ. This represents a reduction of about 37% in the RMS value compared to the pre-correction result, indicating a significant improvement in measurement accuracy. The proposed method offers advantages including ease of implementation, low hardware requirements, and reliable measurement accuracy.

During on-orbit operation, space cameras are exposed to complex thermal environments. Non-uniform variations in the structural temperature field can induce thermoelastic deformation, leading to line-of-sight (LOS) pointing deviations and significantly degrading imaging accuracy and stability. To address the insufficient robustness of the traditional Least Squares (LS) method in analyzing LOS pointing stability of space cameras under complex thermal conditions, this paper proposes a thermal line-of-sight pointing analysis method based on the Iteratively Reweighted Least Squares (IRLS) algorithm. First, a thermo-structural coupled model of the space camera is established to analyze the mapping relationship between temperature field variations and LOS pointing deviation. Then, the IRLS algorithm is introduced to perform robust estimation of model parameters. By constructing a weighted residual function, the influence of abnormal measurement data on parameter identification is effectively suppressed, thereby improving the prediction accuracy of thermal deformation. Meanwhile, an energy-iterative window adaptive centroiding algorithm is adopted to capture the variation of spot centroid positions with temperature changes. To investigate thermally induced pointing drift of the on-orbit camera, thermal experiments are conducted. Simulation results are further validated using ground-based thermal test data, and the performance of the proposed IRLS method is compared with that of the traditional LS method in terms of pointing error prediction accuracy and convergence characteristics. The results demonstrate that the proposed IRLS-based thermal analysis method significantly improves the prediction accuracy of LOS pointing deviation in the presence of measurement noise and outliers, while enhancing the stability and robustness of the model. This approach provides an effective technical solution for on-orbit thermal deformation compensation and accuracy maintenance of high-resolution space cameras.

In real-time brain neural observation of freely moving animals, the miniature head-mounted fluorescence microscope is currently one of the most advanced brain science observation instruments. However, most existing miniature fluorescence microscopes, in order to meet strict size and weight constraints, have a limited field of view, making it impossible to simultaneously observe neural activity in multiple brain regions. On the other hand, a few products with a larger field of view are too heavy to be worn on small animals. This study employs lightweight, planar, and high-quality gradient refractive index lenses to reduce the microscope's weight while ensuring a large field of view. Using gradient refractive index lenses for the design of a large-field-of-view miniature fluorescence microscope, this research derives the off-axis aberration formula for oblique light incidence on gradient refractive index lenses, analyzes the refractive index distribution model and aberration correction of these lenses, and designs a miniature fluorescence microscope with a 4 mm×4 mm field of view, a numerical aperture (NA) of 0.1, and a prototype weight of only 2.89 g. The central visual field resolution is 13.9 μm, preliminarily achieving the resolution for neural cells in freely moving mice.

Aiming at the problem that existing spectral compressed sensing algorithms adapted to the visible band are difficult to achieve high-precision reconstruction for sharp gas absorption features in the mid-wave infrared (MWIR) spectra, this paper proposes a physics-driven MWIR spectral compressed encoding and reconstruction network to realize high-precision reconstruction of MWIR spectra with sharp gas absorption features. The dual-branch MWIR spectral reconstruction network serves as the core module of the proposed framework. Specifically, the network consists of two parallel branches, namely the smooth background reconstruction branch and the characteristic absorption reconstruction branch, which respectively realize the accurate reconstruction of smooth background logarithmic spectrum and sharp gas characteristic absorbance. Subsequently, high-accuracy reconstruction of MWIR gas absorption spectra is achieved through information fusion, physical quantity conversion, and post-processing with fully connected layers. Experimental results on the reconstruction of gas absorption spectra within the 3.7−4.8 μm band with 45 channels in real-world scenarios demonstrate that the proposed method achieves a peak signal-to-noise ratio (PSNR) of more than 28.159 dB and a spectral angle mapper (SAM) value of better than 0.053 rad. For a data cube with an image resolution of 320×256, the reconstruction time is approximately 0.65 seconds. This method effectively breaks through the technical bottleneck of high-precision MWIR spectral reconstruction, and it features both the interpretability of physics-driven models and the generalization capability of data-driven models. It provides a feasible technical path for MWIR spectral compressed sensing and exhibits significant potential for practical applications.

To address the low optical efficiency in the peripheral regions of large-scale solar power tower heliostat fields, this study proposes an overlapping layout optimization method and a multi-target aiming strategy for triple-tower solar thermal power plants. First, Particle Swarm Optimization (PSO) is utilized to determine the optimal configuration for a single-tower layout. These individual fields are then arranged, and the optimal overlapping triple-tower layout is established by refining the inter-tower distances. Finally, a multi-target aiming strategy is implemented for heliostats within the overlapping zones based on their instantaneous optical efficiency. By modeling the solar concentration process and comparing layout configurations, the results demonstrate that the annual average optical efficiency of the overlapping triple-tower field is 0.24% higher than that of the distributed counterpart. Furthermore, the overlapping arrangement is more compact, resulting in a significantly reduced land footprint.

Space-based gravitational wave detection uses laser heterodyne interferometry to measure picometer-level displacement fluctuations of test masses separated by millions of kilometers. The interferometric system must achieve picometer-level accuracy in the millihertz frequency band. In the interferometer, test-mass rotation limits system sensitivity through two types of coupling errors: rotation–rotation coupling and rotation–translation coupling. This paper systematically investigates the mechanisms of these two errors and adopts a sequential suppression strategy: rotation–rotation coupling is first suppressed, followed by rotation–translation coupling.A test-mass interferometer is developed based on laser heterodyne interferometry and wavefront sensing, enabling high-sensitivity displacement and angular measurement as well as noise analysis. The coordinate transformation between the steering mirror and the detector is experimentally calibrated. The steering mirror is then rotated to the minimum-coupling angle, aligning the two coordinate systems and suppressing rotation–rotation coupling. An optical model is further established based on geometric relationships, and its parameters are experimentally calibrated. A real-time compensation system is developed to dynamically suppress rotation–translation coupling.After suppression, the rotation–rotation coupling coefficient is approximately 12.5 mrad/rad. The rotation–translation coupling error is reduced by about 90% in the time domain and by approximately one order of magnitude in the frequency domain. These results provide a theoretical and experimental foundation for multi-degree-of-freedom decoupling and noise suppression in interferometers for space-based gravitational wave detection.

To overcome the formidable challenges of suppressing laser frequency noise and clock noise in millihertz-band space-borne gravitational wave detection, as well as the inherent complexity and limitations of conventional second-generation Time-Delay Interferometry (TDI) schemes, this study proposes an innovative payload architecture and noise suppression strategy based on Space-borne Optical Clocks (SOCs). We first detail the core payload design, which replaces the traditional Ultra-Stable Oscillator (USO) on each spacecraft with an advanced SOC system. Subsequently, we introduce two synergistic noise suppression mechanisms: locking the laser strictly to atomic transition frequencies, and employing optical frequency combs (OFCs) to down-convert the optical clock frequency into a highly stable microwave clock signal. Drawing upon the stability parameters of state-of-the-art SOCs, the system's noise suppression performance across the target frequency band of 0.1 mHz to 1 Hz is comprehensively verified through both theoretical analysis and numerical simulations. The results demonstrate that the proposed scheme suppresses laser frequency noise and clock noise by two and three orders of magnitude in the millihertz band, respectively, ensuring that the residual noises remain well below the stringent noise floor required for the mission. Remarkably, this architecture enables the first-generation TDI technology to fully satisfy the mission requirements, thereby eliminating the need for additional complex clock-noise-removal algorithms. Consequently, while preserving high detection sensitivity, this scheme drastically enhances the simplicity and robustness of the data processing pipeline, and significantly relaxes the rigorous precision constraints typically imposed on inter-spacecraft ranging and clock synchronization. As SOC technology continues toward miniaturization, the proposed framework exhibits substantial application potential for future space-borne gravitational wave observatories.

In space-based gravitational wave detection, the Point-Ahead Angle Mechanism (PAAM) is crucial for high-precision pointing of intersatellite laser links, but its rotation introduces tilt-to-length (TTL) noise that severely limits interferometric accuracy. To suppress local TTL noise caused by PAAM angular jitter, this paper proposes an imaging system that optically images the detector onto the equivalent rotation center of the PAAM, actively mitigating geometric TTL noise. A highly symmetric equal-arm heterodyne interferometer test platform was constructed, and IFOCAD simulations were performed to evaluate suppression performance under non-ideal conditions (angular jitter, rotation center offset, installation errors, thermal deformation). Results show that under ideal alignment, the imaging system suppresses 98.9% of lever-effect optical path changes and 98.2% of piston-effect changes. With installation errors, TTL noise is suppressed within $ 1\;\text{pm/}\sqrt{\text{Hz}} $, and remains below $ 10\;\text{pm/}\sqrt{\text{Hz}} $ when thermal noise is introduced. Simulations confirm that lever noise has a second-order correlation with angular jitter, while piston noise has a first-order correlation, consistent with theoretical analysis. This study provides theoretical and simulation support for designing high-stability beam pointing control systems and assessing noise in future missions.

This paper studies the phase meter applied to space laser interferometry. The phase-locked loop will suffer from lock loss in actual operation. Researchers commonly adopt the FFT frequency measurement method to re-acquire the signal at the present stage. This method has obvious technical defects. Its frequency measurement accuracy is low at the order of 100 Hz, and the relocking time is long about 7 ms. This paper proposes an automatic relocking technique deployed in collaboration with FFT. This technique adopts a lock-loss detection strategy that combines instantaneous frequency values and frequency change rates. It selects two data sources to judge lock loss, including the original data of the loop filter and the down-sampled data of CIC. It clears the integration error through the reset operation after lock loss occurs, and it receives the predicted value output by the frequency prediction algorithm. The frequency prediction algorithm uses the waveform generation algorithm for periodic signals. It uses the second-order polynomial prediction algorithm for aperiodic signals. It also combines interpolation technology to generate the corresponding frequency predicted value. The automatic relocking technique and FFT are deployed in parallel, and they form a clear functional division. This technique performs frequency prediction based on the inherent regularity of the signal. It deals with lock-loss scenarios of all regular signals regardless of the lock-loss duration. It also realizes fast relocking of short-time irregular signals within 1 s. FFT is responsible for signal re-acquisition in irregular signal scenarios and long-time complex lock-loss scenarios. The two methods form a working mode with complementary advantages. Experimental verification results show that the algorithm proposed in this study has an average relocking time of 32 μs and a maximum relocking time of 60 μs in the scenario of regular signal lock loss. The performance is improved by two orders of magnitude compared with the FFT method. The relocking speed has no correlation with the lock-loss duration. It can still maintain the relocking speed at the order of tens of microseconds when the lock-loss duration reaches 10 s. The frequency estimation error is stably controlled below 10 Hz in the signal-to-noise ratio range from −10 dB to 10 dB. The system can still achieve stable locking even when the signal-to-noise ratio is as low as −10 dB. This architecture deployed in collaboration with FFT retains the wide-band acquisition capability of FFT. It significantly improves the fast relocking capability in regular signal scenarios. It provides high-precision, fast-response and high-stability phase measurement technical support for space gravitational wave detection missions.

The Space Gravitational Wave detection program intends to use three satellites in space to establish an equilateral triangle constellation structure, and realize the detection of gravitational wave signals in the middle and low frequency bands by laser heterodyne interference. Laser capture and pointing technology is used to achieve high-precision alignment of beams between satellites, and the construction of three bidirectional laser links is realized. Differential wavefront sensing (DWS) technology is the core of laser tracking and pointing stage, and it is the key to achieve nanoradian Angle resolution. In order to fully verify the on-orbit feasibility of the laser capture and tracking system, it is necessary to carry out long-distance ground verification experiments on the principle prototype. However, the transmission of light in the atmosphere will seriously affect the Angle measurement ability of DWS technology, and it is urgent to find a scheme to suppress the interference. Therefore, this paper systematically analyzes the influence of atmosphere on DWS by means of numerical simulation, and proposes the introduction of adaptive optics technology to compensate the interference of atmosphere on DWS signal for the first time. Then, a laser tracking and pointing experimental system with dual control loops based on DWS signal and wavefront measurement is designed and built. The experimental results show that in the 0.1 Hz−1 Hz frequency band, the performance of the same frequency band can be improved by about 10 times, which fully demonstrates that the adaptive optics system can effectively improve the measurement ability of DWS in the atmospheric environment, laying a foundation for the subsequent long-distance ground verification of laser capture and pointing system in atmospheric environment.

Due to the in-situ antagonism and site competition during multi-ion coexistence in real water environments, traditional linear sensing models often fail. In this study, nitrogen-doped carbon dots (N-CDs) synthesized via a one-step hydrothermal method were used as a platform to investigate the microscopic response mechanism in Cu²⁺ and Fe³⁺ coexisting systems by constructing a 2D cross-fluorescence response matrix. Firstly, the fluorescence quenching evolution under different interference backgrounds was experimentally observed. The results showed that under a high concentration Cu²⁺ background, the fluorescence response induced by Fe³⁺ exhibited significant nonlinear shifts and quenching stagnation, confirming the intense exclusive competition between the two ions at the nano-interface. Subsequently, to analyze this nonlinear process, a "four-state physical kinetic model" was constructed based on the principle of detailed balance, and a global response analytical expression containing the thermodynamic synergy factor ($ \alpha $) was derived. Finally, a global surface fitting was performed on the experimental response matrix using the theoretical model. The results demonstrated a high degree of agreement between the theoretical fit and experimental data, yielding a synergy factor of $ \alpha $ ≈ 0.015. This extremely low value quantitatively confirms the extreme physical shielding and electrostatic repulsion effects constructed by high-valent ions. This study transforms cross-interference into quantifiable intrinsic thermodynamic parameters providing a solid theoretical foundation for nonlinear signal decoding and interface kinetics research in complex systems.

In order to achieve high-precision mass detection of biomolecules, a high-resolution mass sensing scheme based on a hybrid spinning optomechanical system is proposed, in which a spinning whispering-gallery-mode optomechanical cavity driven by a phonon pump is coupled to another optical gain whispering-gallery-mode cavity. First, the Sagnac effect is generated by rotating the optomechanical cavity clockwise or counterclockwise, enabling nonreciprocal control of the cavity field frequency. Second, an optical gain cavity is introduced to construct a parity-time symmetric or broken system, enhancing the amplitude intensity of the transmission spectrum. Meanwhile, a phonon pump is employed to coherently drive the mechanical breathing mode, further strengthening the optical response of the system. By solving the quantum Langevin equations and applying the input-output formalism, the transmission spectrum of the probe field is obtained. When biomolecules (such as baculoviruses or coronaviruses) are deposited on the surface of the optomechanical cavity, the mass of the target molecules can be retrieved by monitoring the resonance frequency shift of the mechanical sideband peak in the transmission spectrum. Numerical results show that the Sagnac effect, optical gain cavity, and phonon pump collectively enhance the amplitude intensity of the transmission spectrum, thereby improving the sensitivity of mass sensing. Compared with conventional optical mass sensing schemes based on single-cavity optomechanical systems, the sensitivity of the proposed scheme is improved by approximately one order of magnitude, and the minimum detectable mass reaches the picogram level (~1 pg). This scheme achieves ultrasensitive, high-resolution biomolecule mass detection and provides a new physical platform for chip-scale ultrahigh-resolution sensing devices.

Weak measurement technique based on weak-value amplification offers an effective method to detect the tiny spin splitting in the photonic spin Hall effect. However, its performance is constrained under conditions of strong coupling or near-orthogonality between the pre- and post-selected states. Based on differential interference theory, this work establishes a relation between the spin-dependent displacement and the amplified displacement for vortex beam with arbitrary topological charge under partial reflection at an air–glass interface. The relation remains valid even under strong-coupling conditions or when the pre- and post-selected states are nearly orthogonal, and is applicable for arbitrary incident linear polarizations. The corresponding characteristics of vortex beam reflected at an air–glass interface is systematically analyzed, and the influences of key parameters including the incident angle, topological charge, incident polarization state, post-selection angle, and propagation distance on the amplified displacement are elucidated. This study provides a valuable theoretical foundation for the applications of vortex beam in precision optical measurement and optical micromanipulation.

A low-noise linear-polarization single longitudinal mode (SLM) fiber laser based on polarimetric parity-time (PT) symmetry is proposed and experimentally demonstrated. PT symmetry is achieved within a linear reflection structure. When the balanced gain–loss contrast surpasses the coupling coefficient, the condition for PT-symmetry breaking is met, enabling the realization of an SLM laser. Stable laser output with a high sidemode suppression ratio (SMSR) of 62.6 dB and a high optical signal-to-noise ratio (OSNR) of 64.32 dB is realized. The Lorentz linewidth is measured as 182.5 Hz. The degree of polarization (DOP) and polarization extinction ratio (PER) of the laser remain above 99.8 % and 30.8 dB within 4 hours. Furthermore, the relative intensity noise (RIN) and phase noise of the PT-symmetric laser are analyzed and compared with those of fiber lasers and semiconductor lasers. The results demonstrate the low-noise performance of the proposed PT-symmetric laser.

Dispersion scan (D-scan) is an ultrashort laser pulse characterization technique based on dispersion modulation and nonlinear spectral response, and, owing to its extremely simple optical configuration and high sensitivity to broadband spectra and phase evolution, it has developed into an important tool in the field of ultrashort pulse characterization. Focusing on the ability of D-scan to meet the demands of real-time operation and robustness, as well as its extension toward extreme parameters such as single-cycle pulses and the deep-ultraviolet region, this paper systematically reviews the key progress of D-scan technology in terms of retrieval algorithm optimization and experimental scheme expansion. First, the evolution of D-scan retrieval algorithms is summarized. This progression traces the shift from early Nelder–Mead and differential evolution algorithms to the current standard generalized pulse retrieval algorithm, and ultimately to deep-learning-based techniques that enable millisecond-level, real-time reconstruction. Particular emphasis is placed on the improvements in computational speed, algorithmic robustness, and noise immunity achieved across these diverse approaches. Regarding experimental techniques, the paper examines second-harmonic-generation (SHG) D-scans based on second-order nonlinearities. It details the technological transition from conventional scanning methods to real-time, single-shot measurements, and highlights recent progress in applying SHG D-scans to vectorial optical field characterization. Subsequently, to circumvent the physical limitations of second-order nonlinearities—specifically concerning multi-octave spectral overlap and phase matching in the DUV region—this review further explores D-scan techniques leveraging third-order nonlinear effects and their derivatives. It elucidates how these methodologies push the application boundaries of D-scan toward the single-cycle limit and into the DUV regime. Finally, current challenges confronting D-scan technology are outlined, including its reliance on external components and its extension to longer wavelengths and longer pulse durations. The paper concludes with an outlook on the future trajectory of D-scan technology within strong-field physics and attosecond science.

To enable low-cost and efficient characterization of EUV photoresists, a lithographic evaluation system based on a tabletop high-harmonic generation (HHG) source and a reflective interferometer was developed. High-order harmonics were generated in argon using a 515 nm femtosecond laser. After focusing by a toroidal mirror and spectral dispersion by a blazed grating, the 11th harmonic (46.8 nm) was selected through a slit as the EUV source. Nonchemically amplified resists based on oxime sulfonate-functionalized polystyrene (PSOS) were used as the test material, and interference exposure was performed with a Lloyd’s mirror and a symmetric dual-mirror configuration. To solve the alignment problem between the sample plane and the symmetric dual-mirror interferometer, an optical ranging method based on diffraction-fringe inversion was proposed, enabling precise positioning of the symmetric dual-mirror interferometer. The results show that the Lloyd’s mirror produces clear high-contrast line-space patterns with a period of 125 nm and enables characterization of the tested resist at the 100 nm scale. After precise positioning by diffraction-fringe inversion, the symmetric dual-mirror configuration produces line-space patterns with a period of 60 nm, significantly improving the system resolution. This evaluation system provides a low-cost and scalable experimental platform for rapid screening of photoresist materials, investigation of resolution limits, and development of related lithographic processes.

Virtual staining leverages deep learning to transform label-free images into fluorescence-specific images, markedly reducing the complexity and phototoxicity of live-cell imaging and enabling high-resolution, multi-channel, high-throughput, and long-term acquisition, which is of great significance for biomedical research. Existing methods mostly rely on supervised learning with paired data. To reduce the dependence of virtual staining on paired data and further improve the quality of generated images, this paper proposes an unsupervised virtual staining framework, MVS-CycleGAN, which integrates a masked self-supervised mechanism.Without requiring paired images, MVS-CycleGAN introduces a random masked reconstruction task that occludes parts of the input and forces the network to complete the missing regions using semantic context. This design allows the model to capture both global morphology and local texture in the target domain, imposing effective semantic constraints and alleviating the semantic drift commonly observed in cross-domain translation with conventional unsupervised models. Experiments on three cell datasets demonstrate that MVS-CycleGAN consistently outperforms traditional approaches: FSIM reaches 0.784/0.565 on BJ-5ta membrane/nuclei, 0.854/0.830 on HEK293T, and 0.657/0.740 on Neuromast (corresponding improvements of 1.03%, 9.50%, 1.07%, 0.85%, 1.08%, and 5.56%, respectively). In addition, downstream segmentation experiments further confirm the effectiveness of the virtually stained images for quantitative analysis. These results indicate that the proposed method provides a feasible solution for extending virtual staining to diverse biomedical scenarios.

We presents a novel prism-coupled packaging strategy for WGM Resonators. Utilizing an all-solid-state optical adhesive process combined with active temperature control and hermetic sealing, the proposed package exhibits exceptional long-term stability and environmental robustness. The standalone WGMR module was fully characterized, demonstrating a temperature sensitivity below 10⁻⁷/°C and a low-frequency Z-axis acceleration sensitivity below 10⁻¹⁰/g. Furthermore, the application of this module was explored as a stable optical frequency reference and a nonlinear photonic platform, achieving a short-term frequency stability of 2×10⁻¹³ at 2 ms and generating Kerr soliton microcombs with a pump power of 100 mW. This compact, robust, and stable packaging solution significantly enhances the immediate applicability of WGMRs in real-world applications such as narrow-linewidth lasers and portable microcombs, thereby facilitating the transition of WGMR technology from laboratory research to practical deployment.

Our work presents a spacetime crystal metasurface antenna based on substrate integrated waveguide (SIW). It addresses the limitations of traditional magnetic non-reciprocal devices, such as large volume, high cost, and significant losses. The proposed antenna enables compact, efficient, magnetless non-reciprocal radiation and beam manipulation. An FPGA (Field Programmable Gate Array)-controlled PIN diode array is employed to implement equivalent dynamic traveling-wave modulation on the SIW surface. A dispersion model, combining Floquet-Bloch theory and the transfer matrix method, elucidates the dynamic dispersion characteristics and the harmonic mode selection mechanism in the time-varying system. Experimental results demonstrate that, under waveguide port excitation, the system generates multi-beam radiation governed by frequency-momentum mapping. In contrast, under free-space incidence conditions, a deterministic non-reciprocal spectral transition is observed, where the signals undergo frequency up-conversion according to a harmonic order-doubling rule. The device achieves a maximum non-reciprocal isolation of 17.9 dB, confirming the breaking of time-reversal symmetry in both the first- and higher-order harmonic channels. This work validates the effectiveness of SIW-based spacetime coding technology for constructing magnetless non-reciprocal devices, providing a promising technological approach for frequency conversion, unidirectional transmission, and pseudo-Doppler effects in next-generation intelligent wireless communication systems.

To achieve the generation of ultrashort isolated attosecond pulses using few-cycle pulses, it is necessary to study the precise control of the electric field of few-cycle light through double optical gating technology. In conventional experiments, double optical gating typically regulates multi-cycle pulses, and the analysis does not consider higher-order dispersion during laser propagation in media, second-harmonic conversion efficiency, or the exact waveform of the second-harmonic electric field. However, such approximations are no longer valid for few-cycle pulses. This paper accurately simulates the propagation and second-harmonic generation process of few-cycle pulses in nonlinear crystals based on a coupled-wave equation model, revealing the key influence of dispersion effects and other factors on the gating waveform. The research shows that when the driving light field is a few-cycle laser pulse, the traditional electric field estimation method for double optical gating is no longer applicable. Few-cycle pulse lasers have an ultra-broad spectrum, and effects such as group velocity mismatch, phase mismatch, and dispersion caused by differences in phase accumulation among different wavelength components become significantly more pronounced compared to long pulses. For a few cycle pulse, the optimal gating light field can be achieved by adjusting the thickness of the beta-barium borate (BBO) crystal in the double optical gating setup to 126.4 μm. This paper proposes that coordinated adjustment of the waveplate and BBO crystal thickness can finely tune the relative delay between the driving field and the second-harmonic field, thereby optimizing the gating electric field and the driving electric field, providing effective parameter optimization guidance for the generation of ultrashort isolated attosecond pulses.

With the advancement of photoelectric technology, optical films are extensively employed in military, medical, and communication fields. Film thickness is a critical parameter that determines optical performance, and the accuracy of its monitoring system directly affects spectral characteristics. To mitigate the significant thickness control errors in conventional direct monitoring systems—caused by light source divergence and weak detector response signals—this paper proposes an externalized optical configuration. In this design, both the optical transmitter and receiver are placed outside the vacuum chamber, thereby avoiding interference from chamber vibration, temperature variations, and assembly inconsistencies. Additionally, an optical signal modulation scheme based on fiber coupling and collimation-focusing is introduced. By adopting an external integrated light source combined with multimode optical fibers and a composite optical path, and by optimizing component parameters through optical simulation to improve spot quality and energy density, the stability of both optical and electrical signals is enhanced. After optimization, irradiance at the fiber receiving end increased by 222.7%, signal strength by 156.6%, and the signal-to-noise ratio by 70.38%. The system’s performance was validated by preparing a narrowband filter film with a center wavelength of 2400 nm and a bandwidth of 40 nm, achieving a wavelength deviation within 1 nm over three repeated tests while consistently maintaining the 40 nm bandwidth. These results confirm that the system enables high-precision and stable film thickness monitoring even in spectral bands with weak detector response.

Single-frame image deblurring remains an inherently ill-posed problem. Furthermore, existing diffusion models suffer from high inference latency, while state space models lack sufficient cross-modal interaction capabilities. To overcome these limitations, we propose an end-to-end Event-fusion Multi-head Attention Network (EFMAN) that exploits high-frequency spatiotemporal priors from event cameras for high-quality image restoration. Specifically, a cross-modal adaptive attention mechanism is designed to precisely align asynchronous high-frequency event streams with synchronous RGB features in both spatial and temporal dimensions, thereby compensating for exposure deficiencies. To mitigate the impact of inherent sensor noise, a Feature Enhancement Attention (FEA) module bolsters feature robustness against noise via global context modeling. Additionally, a Lightweight Channel-Spatial Attention (LCSA) module is integrated to adaptively recalibrate feature responses while substantially alleviating computational redundancy. These components are optimized by a multidimensional joint loss function—encompassing pixel, feature, and gradient domains—to synergistically enforce multi-scale constraints, ensuring consistency between micro-textures and global topologies. Extensive experiments demonstrate that EFMAN significantly enhances deblurring performance while maintaining efficient inference. Compared to state-of-the-art methods, our approach achieves maximum PSNR and SSIM improvements of 1.19 dB and 0.005 on the GoPro dataset, and 0.38 dB and 0.003 on the REBlur dataset, respectively. By effectively addressing the challenges of multi-modal alignment and noise interference, EFMAN strikes an optimal balance between restoration quality and computational efficiency, making it highly suitable for clear image reconstruction in high-dynamic-range and rapid-motion scenarios.

The microwave photonic filter based on weighted delay structure simultaneously leverages the advantages of photonic and radio-frequency components, featuring reconfigurability, low cost, and wide bandwidth, providing flexible and efficient signal processing capabilities in the microwave band. However, due to the complexity of the weighted delay structure, discrete optoelectronic components in the system can interfere with the weighted taps at different wavelengths—such as the envelope and gain competition of optical frequency combs, the gain non-uniformity and nonlinearity of EDFA, and the limited filtering bandwidth of modulators. These factors cause deviations in the weighted taps from their designed values, leading to distortion in the microwave filter. This paper proposes an end-to-end optimization approach by treating the microwave photonic filter as a black-box system. By monitoring the spectral shape (i.e., the weight values of each tap) of the final output in real time, the difference between the wavelength taps and the ideal taps is calculated and feedbacked to adjust the filtering coefficients of the waveshaper in real time, ensuring the output spectral weights remain in the designed state. Through this end-to-end optimization approach, we achieved a spectral reconstruction accuracy of 0.05dB and completed an RF low-pass filter with an out-of-band rejection ratio of up to 47dB.

Addressing the requirement for infrared detection of ship wakes under complex sea conditions, a method for analyzing the dynamic infrared polarization characteristics of ship wakes based on the microfacet model is proposed. An analytical model for the infrared polarization effects of wakes against a complex sea surface background is constructed. Based on the P-M sea spectrum model and the Kelvin wake model, the microfacet bidirectional reflectance distribution function is introduced to analyze the infrared polarization characteristics of ship wakes under dynamic sea surface backgrounds. The influence of parameters such as ship speed, draught, wind speed, and wind direction on the wake's infrared polarization characteristics, including the degree of polarization (DOP), angle of polarization (AOP), and contrast, is investigated. Notably, the average contrast of the wake's infrared DOP image is improved by 159% compared to traditional intensity images, and the AOP image shows an improvement of 258%. The analytical model for wake infrared polarization effects is validated by comparing mathematical simulations with computational fluid dynamics simulations, achieving a similarity of over 95.7%. A comparison between actual captured wake images and simulation results shows high similarity, confirming the effectiveness of the proposed model for simulating and analyzing the infrared polarization characteristics of ship wakes against a sea background. This study provides an important theoretical foundation for high-precision, anti-interference detection and identification of ships under complex sea conditions.

The quality of underwater imaging significantly deteriorates due to underwater light field which caused by multiple scattering of water. In order to quantitatively analyze the quality degradation of underwater image, it is necessary to study the distribution of underwater light field and establish a strict underwater image transmission model. Assuming that water VSF is spherical symmetry, underwater light field distribution formed by an ideal point light source is calculated, and then water PSF is obtained by brightness integral along the path. Finally, water MTF in the spherical space is derived by means of mathematical tools such as spherical harmonic function and spherical convolution. Under the condition that the intrinsic optical parameters of water are known, curves of water MTF and contrast limit factor are presented. The algorithm model solves the derivation of water MTF under the condition of spherical water VSF, and this lays a foundation for the derivation of water MTF under the condition of non spherical water VSF and dynamic light field.

High-power, high-beam-quality short-pulse/ultrashort-pulse green lasers have wide applications in industry, medicine, and scientific research. To clarify the research progress of green light sources based on second-harmonic generation (SHG, frequency doubling), this paper systematically reviews the latest advancements in SHG green light sources at kilohertz repetition rates, categorized by pulse width and doubling scheme into four types: nanosecond intracavity doubling, nanosecond extracavity doubling, picosecond extracavity doubling, and femtosecond extracavity doubling. For nanosecond intracavity doubling, crystals such as KTP and LBO are used, with power increased to 51.1 W (energy 50 mJ, repetition rate 1 kHz) and efficiency of 50%. Nanosecond extracavity doubling primarily employs LBO, where tandem frequency-doubling crystals can elevate the doubling power to 1.04 kW (energy 1.04 J, efficiency 89%). Picosecond extracavity doubling achieves the highest average power of 1460 W (energy 259 mJ, efficiency 71%). Femtosecond doubling, by employing thin crystals, boosts power to 29 W (energy 440 μJ, efficiency >52%). The advancements in SHG-based green light sources and related application technologies will continually expand their boundaries in scientific research, industry, medicine, and other fields.

To An all-silica fiber-optic Fabry-Perot (F-P) high-temperature vibration sensor is proposed to address sensor failure and signal distortion in extreme environments. A collimated coupling structure based on a silica ball lens enables integrated, non-contact signal transmission between the fiber and the sensitive structure. The sensitive units are batch-fabricated using MEMS and thermal pressure bonding technologies. By combining three-wavelength dynamic demodulation with spectral cross-correlation, precise vibration signal extraction and temperature compensation are achieved, effectively eliminating thermal cross-sensitivity. Experimental results indicate that as the temperature increases from room temperature (23 °C) to 800 °C, the sensitivity of the sensor decreases from 1.051 nm/g to 0.8915 nm/g. After temperature compensation, the maximum residual sum of squares (RSS) of the sensor is 0.168, and the full-scale nonlinearity error does not exceed 1.033%. In dynamic response tests, the characteristic frequency of the sensor is considerably higher than 6000 Hz. The sensor exhibits high flatness within the frequency response range of 100−2000 Hz, and its sensitivity gradually increases between 2000 Hz and 6000 Hz, with a maximum increment of only 0.177 nm/g. Featuring high consistency, adhesive-free integration, and electromagnetic immunity, this sensor provides a robust solution for vibration measurement in high-temperature environments.

The mirror is one of the great significance components of the space camera, and the aluminum alloy mirror is becoming one of the development directions of space camera mirrors with its excellent processability. Objective: To reduce the difficulty of installing and adjusting space cameras, an monolithic aluminum alloy mirror structure design was carried out. Method: First, based on the concept of integrating multiple functions such as mirror surface, flexible support, installation reference and so on, the structure design of an monolithic mirror was carried out. Besides, while designing the structure, co-reference process design was conducted simultaneously. This design was informed by establishing an error transmission model and a corresponding precision allocation scheme. Finally, simulation analysis and processing were carried out on the designed mirror. Result: The results show that the surface accuracy variation of the monolithic mirror was less than RMS 0.01λ@632.8 nm under typical working conditions, and the precision of the processed mirror could reached up to RMS 0.016λ@ 632.8 nm, and the deviation between the mechanical and optical references was better than 2". Conclusion: The monolithic aluminum alloy mirrors designed in this study can satisfy the space mirror requirements of stability, high precision and excellent consistency.

During downward laser transmission across the air–sea domain, beam propagation is influenced by a range of complex, multi-source and multi-scale perturbations, including atmospheric turbulence, fluctuations at the air–sea interface, and oceanic turbulence. This study investigates the evolution of beam spatial coherence and introduces an analytical approach based on a composite perturbation model. The composite model integrates Kolmogorov turbulence theory, the Pierson–Moskowitz (P–M) sea-surface wave spectrum, and the slant-path oceanic refractive-index power spectrum. By employing the Rytov approximation, analytical expressions for the mutual coherence function and wave structure function are derived, with particular focus on the wave structure function of a Gaussian beam propagating through slant-path oceanic turbulence. Each component of the model has been individually validated. Experimental results demonstrate that variations in turbulence intensity, propagation distance, and environmental parameters significantly affect beam spatial coherence, thereby exerting a substantial impact on the performance of cross-domain optical communication systems. Compared to single-turbulence approximation models, the proposed composite perturbation model effectively reduces the spatial coherence bias by approximately 20%-30%, revealing the influence mechanisms of multi-source perturbations on coherence evolution. This model provides an effective theoretical foundation for the performance evaluation and optimization of air–sea optical communication links and enhances the stability and reliability of optical communication systems under realistic conditions.

Objective: To retrieve the pulse information from the dispersion scanning (d-scan) trace, a differential evolution (DE) algorithm is used. Methods: A partially coherent pulse train is generated and then test by traditional DE algorithm and its improved version. Results: The errors retrieved using the traditional and improved DE algorithms are 7% and 1%, respectively. Conclusion: The improved algorithm can more accurately retrieve the d-scan trace of partially coherent pulse train.

Due to the nonlinear effects produced by the actual defocusing projection system, which affect the accuracy of phase measurement, the phase error of binary fringe defocusing projection was studied. Based on the analysis of the current study status in the field, an expression for the intensity distribution of deformed fringe pattern signal in nonlinear systems is given, and the reasons for both high-order spectra components occurrence and their mixing with the fundamental frequency components, resulting in spectra overlapping, are analyzed. The method of defocusing the projector was employed to remove the higher-order harmonic components in the spectra domain and filter out one of the fundamental frequency components. An inverse Fourier transform was then performed on the spectra to obtain the expression of fringe intensity in the spatial domain. The continuous phase containing continuous signals was obtained using the phase-shift algorithm and phase unwrapping, and the expression for phase error after unwrapping in actual measurement systems was derived. The correct analysis of the basic principles has been verified through simulation and experiments. The simulation results indicate that the errors value obtained by the method mentioned in this paper are 34.51% for the binary fringe defocusing method, 44.83% for method of reference [1], and 67.83% for method of reference [10], respectively. The experiment results indicate that the phase recovered by using our method has good effects, and the corresponding phase error is relatively small.

Chiral metasurfaces play critical role in physics, materials science, pharmacognosy, and communications. To achieve high-performance chiral responses, such as high circular dichroism (CD) and high-quality factors (Q-factors), BIC-based metasurfaces have been extensively studied as a promising platform. However, most realized BIC metasurfaces rely on metallic constituents whose high electromagnetic losses and absence of dynamic chirality tuning together impose a severe limit on their practical potential. This paper presents an all-dielectric chiral BIC metasurface. By illumination symmetry breaking, the metasurface exhibits a CD value of 0.93. Additionally, dynamic tuning of CD is enabled by external optical pumping. This scheme provides a new avenue for dynamically manipulating the chiral metasurface, which can be used to achieve more complex dynamic chiral characterization and applications.

Diffractive waveguides have emerged as a particularly promising solution for augmented reality (AR) near-eye display technologies. These waveguides are characterized by their light weight, wide field of view, and large eyebox. However, most commercially available AR waveguide simulation software has been developed by foreign companies, and there has been little advancement in domestic 3D visualization software for optical waveguide design and simulation. The present study is, to the best of our knowledge, the first to develop 3D visualization module for optical waveguide design and simulation based on ray-field tracing. Using this module, a two-dimensional exit-pupil-expansion diffractive waveguide has been designed, and a systematic design workflow is demonstrated. The workflow integrates k-domain analysis, automated layout generation of grating regions within the optical waveguide, waveguide optimization, and ray-field tracing simulations, thereby establishing a cohesive methodology for device development. The module extends beyond single-waveguide simulations to system-level analyses of near-eye displays, including micro-displays, micro-projectors, and human eye models. By bridging the microscopic and macroscopic scales, it enables holistic performance evaluation of AR optical systems, highlighting their capabilities and technical advantages. This module provides a robust and efficient platform for domestic optical engineers to advance the design and simulation of optical waveguides, thereby accelerating the industrialization and technological advancement of AR optics in China.