Focusing on the key problem of establishing inter-spacecraft laser links for space-borne gravitational wave (GW) detection, this paper presents a high-precision beam pointing control scheme founded on multi-source information fusion. A detailed state-space model is constructed by integrating the coupled dynamics of moving optical sub-assemblies. Using error quaternions, the nonlinear measurement equations are linearized, thereby enhancing the accuracy of filter-based attitude determination via inertial sensor fusion. Furthermore, a time-varying analytical formulation of the point-ahead angle (PAA) is derived, supplying a theoretical basis for servo compensation. Closed-loop simulations of a three-spacecraft configuration validate the stability and accuracy of the proposed estimation algorithm. In combination with robust disturbance-rejection control, the method enables highly accurate beam pointing, providing essential technical support for GW detection missions.

Objective: This study addresses fringe-based three-dimensional measurement of local structures on complex reflective printed circuit boards. Uniform image interpolation may distort sinusoidal fringes. Curved fringes may also cause a mismatch between the interpolation direction and local iso-phase lines. Low-modulation regions may further amplify phase errors.Methods: A measurement-oriented phase-preserving fringe super-resolution resampling method is proposed. The super-resolution operation is performed in the gray-image domain. Phase-domain quantities are used as physical constraints. First, a normalized carrier intensity index is used to decouple fringe ridges, valleys, and transition regions. Ridge-valley distance and local modulation are then combined to construct a joint weight. Next, a two-dimensional fringe-alignment displacement field is estimated from multi-frequency phase-shifting data. The field is refined by local correlation and two-dimensional total-variation regularization. The original fringe images are then mapped into an aligned domain for directional interpolation. Finally, a flat/steep-region adaptive fusion strategy is constructed using the displacement-field gradient and local phase variation rate.Results: In the 3 mm, 6 mm, and 9 mm gauge-block experiments, the proposed method reduced the mean absolute error from 0.0290 mm to 0.0208 mm. It also reduced the root mean square error from 0.0428 mm to 0.0295 mm. In the high-reflective PCB pin region and the crystal oscillator package region, the proposed method improved phase continuity and three-dimensional reconstruction stability. In the pin region, compared with image-domain bicubic interpolation, the proposed method reduced the mean absolute error from 0.1753 mm to 0.0254 mm, corresponding to a reduction of about 85.5%. The error standard deviation was reduced to 0.0126 mm.Conclusion:The proposed method improves phase consistency after fringe resampling, increases point-cloud sampling density, and reduces local reconstruction errors in the selected PCB regions. This super-resolution process should be interpreted as sampling-grid densification and interpolation-induced phase-error reduction, rather than as exceeding the true lateral resolution limited by the optical system. The current conclusions are limited to the tested PCB local ROIs and imaging conditions.

Time-interleaved analog-to-digital converters (TIADCs) overcome the sampling rate bottleneck of monolithic ADCs and enable ultra-high-speed broadband acquisition of optical signals in applications such as laser 3D imaging lidar and high-speed optical communication systems. However, their practical performance is fundamentally limited by inter-channel mismatches in offset, gain, and sampling timing, which introduce pronounced spurious components and nonlinear distortion. Such errors directly degrade the sampling accuracy of laser echo signals and impair system ranging and demodulation performance. To address this issue, this paper proposes an all-digital TIADC calibration algorithm based on a multi-channel all-phase fast Fourier transform (FFT) frequency discriminator. A two-stage low-pass filtering and interpolation reconstruction architecture is devised, paired with the multi-channel all-phase FFT frequency discriminator. By exploiting the phase invariance property of all-phase FFT and the phase correlation of multi-channel sampling, the proposed method achieves high-precision frequency estimation and interval discrimination of input signals, which eliminates the inherent high-frequency performance deterioration of traditional algorithms. Integrated with a least mean square (LMS) adaptive filtering framework, the algorithm realizes synchronous joint calibration of offset, gain, and sampling timing mismatch errors. A 4-channel TIADC experimental platform with a total sampling rate of 2 GHz is constructed based on MATLAB and FPGA for performance verification. Experimental results demonstrate that the proposed frequency discriminator maintains a frequency interval discrimination accuracy of 96.7% even at an extremely low signal-to-noise ratio (SNR) of −5 dB. After calibration, the spurious-free dynamic range (SFDR) of the system is improved from 19.8 dB to 81.2 dB, and the signal-to-noise and distortion ratio (SNDR) reaches 73.8 dB. The proposed algorithm operates without dedicated calibration signals and exhibits outstanding calibration performance under low-SNR conditions, providing core technical support for high-speed, high-precision sampling systems in optical fields including lidar and high-speed optical communication.

To address the limitations of conventional conjugate vortex beam interference-based micro-displacement measurement methods, including limited rotation-angle variations of interference patterns and insufficient capability for sub-nanometer displacement detection, a micro-displacement measurement method based on opposed dual-surface differential conjugate vortex beam interference is proposed. The proposed method exploits the linear relationship between the rotation angle of the conjugate vortex interference pattern and the phase difference between two interferometric paths, converting micro-displacement into the angular rotation of petal-shaped interference patterns. To overcome the constraints imposed by camera pixel resolution and pattern distortion on tiny rotation-angle extraction, an opposed dual-surface differential optical path is developed, where two conjugate vortex beams interact with opposite surfaces of the same target. Compared with the conventional single-surface reflection configuration, the proposed structure doubles the relative optical path difference, thereby theoretically doubling the interference-pattern rotation angle under identical displacement conditions. Furthermore, an H-Nets model based on circular harmonic convolution is introduced to extract rotation-equivariant features from the rotating interference patterns. Continuous angular variations are encoded as phase shifts in the complex-valued feature space, enabling stable characterization of tiny rotation angles and accurate displacement inversion. Experimental results demonstrate that, within a displacement range of 0–500 nm, the maximum absolute error is below 0.61 nm, with a mean absolute error of 0.37 nm. The proposed method achieves enhanced micro-displacement measurement accuracy and stability through the synergistic integration of differential optical-path amplification and rotation-equivariant feature decoding.

To address the issue of compensator coupling in the tolerance analysis of high-numerical-aperture microscope objectives, this paper proposes a compensator selection method based on the cosine similarity of the V-matrix, aiming to reduce negative correlations between compensators and avoid problems such as coma and astigmatism that cannot be simultaneously corrected. Taking an infinity-conjugate microscope objective with a numerical aperture of 0.9 as the subject of study, a sensitivity matrix between structural parameters and aberration parameters was constructed using the first-order finite difference method. By employing V-matrix cosine similarity and a weighted greedy strategy, six effective compensators were identified. Experimental results show that the cumulative probability of the system’s wavefront aberration RMS being less than 0.07 λ increased from 47% to 97.7%, while manufacturing and alignment tolerances were reduced from Q1 to Q2 grade, significantly lowering the manufacturing tolerances of the optical system and effectively improving system yield. Alignment simulation experiments further validated the feasibility and effectiveness of this method in high-numerical-aperture microscope objectives. These results demonstrate that this method can select appropriate compensators and effectively reduce the negative correlation among them.

The near-infrared optical absorption and photoresponse of silicon-based optoelectronic devices are intrinsically limited by the bandgap of silicon. Picosecond laser-induced Se doping combined with surface micro/nanostructuring provides an effective approach to enhancing the near-infrared performance of silicon. Among the relevant processing parameters, laser energy density plays a critical role in governing microstructure evolution and dopant redistribution, thereby strongly influencing device performance. In this study, single-crystal silicon substrates coated with a Se film were irradiated using a picosecond laser at energy densities of 0.85, 1.40, and 1.71 kJ/m². Se-doped N⁺−N silicon photodiodes were subsequently fabricated to systematically investigate the effects of laser energy density on surface micro/nanostructure, optical absorptance, and photoelectric performance. The results show that the overall crystalline structure of the samples remains well preserved under all processing conditions, whereas their surface microstructures differ markedly. These structural variations further affect the optical absorption and device photoresponse. At an energy density of 1.40 kJ/m², the sample exhibits the most uniform surface micro/nanostructure. Optical and electrical measurements show that its near-infrared absorptance exceeds 60%, while the corresponding photodiode achieves a responsivity of 2.28 A/W at a reverse bias of −6 V under 1064 nm illumination. These findings demonstrate that picosecond laser energy density plays a significant role in regulating the surface microstructure, near-infrared absorption, and photoresponse of Se-doped silicon. This study provides experimental guidance for optimizing the fabrication and performance of Se-doped black-silicon near-infrared photodetectors.

To meet the stringent requirements of attosecond science, precision manufacturing, and ultrafast spectroscopy for high-performance ultrashort pulses, this study reports the development of a highly stable, self-starting all-polarization-maintaining few-cycle femtosecond fiber laser. A 100.45 MHz all-polarization-maintaining erbium-doped fiber seed source is constructed using a single-walled carbon nanotube film as a saturable absorber. By employing an all-polarization-maintaining bidirectional amplification scheme combined with nonlinear spectral broadening and dispersion management, the system achieves a pulse duration of 30.1 femtoseconds after nonlinear broadening in a polarization-maintaining highly nonlinear fiber and subsequent dispersion compensation. This corresponds to a few-cycle pulse train containing approximately 5.8 optical cycles, with an amplified average output power exceeding 200 milliwatts. Stability measurements demonstrate that the seed source maintains a power root-mean-square fluctuation of only 0.4 percent over 10 hours of continuous operation. Furthermore, after the implementation of temperature control and piezo-electric transducer stabilization for repetition rate locking, the Allan deviation reaches 9.98 × 10⁻¹⁴ over 100 seconds. With its compact architecture and exceptional operational stability, this seed source establishes a robust experimental foundation for the subsequent generation of octave-spanning supercontinuum and high-performance frequency comb applications.

Femtosecond-laser-induced self-organized interference, together with near-field enhancement and incubation effects, enables deep-subwavelength nanoetching. However, the formation of such structures usually relies on random surface scattering centers and multi-pulse feedback, leading to poor uniformity, limited repeatability, and high sensitivity to laser parameters. In this work, a spatiotemporal laser-energy modulation strategy is proposed to improve the writing quality of nanogrooves on 4H-SiC single-crystal surfaces. In the spatial domain, single-slit and double-slit beam shaping are employed to reconstruct the focal-plane energy distribution, suppress lateral energy spreading, and enhance the incubation and self-organized interference effects. In the temporal domain, a GHz burst mode is introduced to regulate the energy-deposition sequence, reduce the instantaneous energy-deposition intensity, and extend the annealing time. Static irradiation and dynamic scanning experiments were conducted to systematically investigate the surface morphology evolution and nanogroove formation mechanism under different modulation strategies. The results show that the elliptical focal spot formed by single-slit shaping enhances the incubation and annealing effects, producing nanogrooves with improved uniformity and edge regularity and a minimum groove width of 62 nm. Double-slit shaping further strengthens the interference-field confinement, reduces the dependence of nanogroove formation on random scattering centers, and decreases the minimum controllable groove width to 34 nm. By introducing GHz burst pulses on the basis of double-slit shaping, stepwise energy deposition through sub-pulses with a 400 ps interval reduces instantaneous strong excitation and suppresses molten redeposition and particle attachment, further decreasing the minimum controllable groove width to 24.5 nm. This spatiotemporal modulation strategy provides an effective technical approach and theoretical basis for high-precision, low-damage, and highly repeatable nanomanufacturing on third-generation semiconductor surfaces.

Ultrafast lasers, owing to their high peak power and ultrashort pulse duration, enable highly precise and localized energy deposition inside transparent glass through nonlinear absorption. This process can induce a variety of micro-modifications, including refractive index changes, nanogratings, and microvoids, and is often accompanied by stress-field modulation and elemental migration in the near-focus region. Such a unique processing mechanism provides an important foundation for three-dimensional micro/nanofabrication inside glass materials. Starting from the interaction mechanism between ultrafast lasers and glass, this paper systematically reviews different types of material modification and their corresponding processing windows, and further summarizes recent progress in applications such as on-chip photonic device fabrication, high-precision cutting, optical waveguide writing, stress-based waveplate fabrication, microchannel processing, and burst-mode ultrafast laser machining. Finally, the paper analyzes the current bottlenecks in processing consistency, mechanistic understanding, and industrial implementation, highlights the importance of inverse engineering for process optimization, and discusses the potential of artificial intelligence technique in complex parameter optimization and intelligent laser processing.

The test mass (TM) in orbit is subject to the charging effect of high-energy particles, which interferes with gravitational wave detection. This paper addresses the charge management requirements of the TianQin Project. First, an electrostatic force model is established to determine the charge threshold of the TM, which is limited to less than 2×10⁻¹³ C. Then, a charge management structure using a UV LED light source is designed, and an engineering prototype is developed accordingly. Finally, a ground testing system based on a torsion pendulum is constructed to evaluate the charge management performance. Experimental results show that at 1 mHz, the resolution of charge measurement is better than 2×10⁻¹⁴ C, and the resolution of charge control is approximately 6×10⁻¹⁴ C, which meet the requirements of space gravitational wave detection. These achievements provide a solid foundation for TianQin project.

To address the issue that traditional static noise superposition methods in space-based gravitational wave detection neglect the dynamic coupling between multi-physics fields and the control system, making it difficult to meet the requirements of high-fidelity mission simulations, it is proposed and designed that a full-chain dynamic simulation system for space-based gravitational wave detection, establishing closed-loop feedback capability between the multi-physics fields and the control system. The system adopts a dynamic closed-loop architecture, comprising a spacecraft multi-physics field simulation module, a full-chain noise simulation module, a drag-free control simulation module, and a data processing and analysis module. In this architecture, the physical field states are computed based on the spacecraft states after control, and noises are generated through full-chain noise models mapped from the physical field states. The system achieves physical source tracing and dynamic simulation of full-chain noises. Simulation experiments reveal that self-gravity acceleration disturbances induced by the motion of the Movable Optical Sub-Assembly (MOSA) and fuel consumption can reach 10⁻¹³ m·s⁻²· Hz^−1/2 level in the observation frequency band（0.1 mHz-1 Hz）, necessitating compensation or subtraction through high-precision in-orbit measurement and calibration methods. The constructed system is capable of capturing dynamic coupling effects neglected by static models, thereby providing a high-fidelity simulation platform for mission design, noise source tracing and sensitivity evaluation in space-based gravitational wave detection.

To address the signal reconstruction problem of high-Q torsion pendulum systems under ground seismic excitation in ordinary laboratory environments—pertinent to ground testing for space gravitational wave detection—a curriculum learning-driven Fourier feature network (FouCLNet) is proposed. Existing hardware isolation strategies impose stringent environmental requirements that are difficult to meet in ordinary ground laboratories. Traditional physics-informed neural networks suffer from spectral bias, gradient conflict, and an inherent tendency for outputs to decay toward zero in high-Q oscillatory systems. Log-spaced Fourier feature mapping is employed with frequency parameters uniformly distributed over the 0.003–0.02 Hz band to match the 0.007 Hz natural frequency of the pendulum. A four-layer fully connected network is constructed, and a hard amplitude constraint loss function is designed to prevent attenuation of micro-radian-scale signals. Through a three-stage curriculum learning strategy, weak physical constraints are progressively introduced with PDE residual weights annealed to the order of 1e-8. Using the torsional response under seismic noise excitation as the target physical quantity and fourth-order Runge-Kutta integration results as ground-truth labels, we randomly sample 80% of time points for training and 20% for in-distribution validation. Experimental results demonstrate that the proposed method achieves a correlation coefficient of 0.9988 on the training set, peak error below 0.4% full scale, 100% amplitude matching, and power spectral density agreement at the 0.007 Hz resonance peak. The in-distribution discrete validation set achieves a correlation coefficient of 0.9958, and the single-point inference latency is merely 0.524 ms. Ablation studies indicate that removing Fourier features or hard amplitude constraints leads to severe model degradation. The pure data-driven configuration achieves good accuracy on the discrete validation set, yet its correlation coefficient drops sharply to 0.511 in continuous-segment reconstruction, whereas the full method maintains 0.986, indicating that weak physical constraints stabilize continuous temporal consistency. Temporal extrapolation beyond the training domain yields a correlation coefficient of merely 0.019, accompanied by spurious low-frequency drift. Furthermore, the model fails to generalize to continuous unseen periods within the training domain (R ≈ 0.029). Consequently, the proposed method is unsuitable for predictive extrapolation beyond the temporal scope of the training data and should be strictly confined to interpolation scenarios within the established training domain. The method provides a high-fidelity in-distribution interpolation reconstruction reference for torsion pendulum systems in ordinary laboratory environments and offers guidance for developing causal real-time vibration suppression algorithms.

To improve the consistency among multiple optical axes in electro-optical pods, this paper proposes two high-precision target center detection methods for optical-axis calibration under complex imaging conditions. For pulsed laser images affected by flicker and burn-mark interference, a staged weighted centroid method is proposed. This method performs coarse localization using large laser spots and then refines the center position using burn marks. For infrared cross targets with blurred edges and noise interference, an intersection optimization strategy based on Hough line screening and directional constraints is proposed. This strategy improves center localization accuracy under weak-edge conditions. Experiments were carried out using multiple laser image sequences and infrared cross-target images. The results show that the root mean square error of the staged weighted centroid method is 0.237 pixels, which is lower than those of the least-squares circle fitting method and the conventional centroid method. For 15 infrared cross-target images, the proposed Hough line screening method achieves an average error of 0.499 pixels and a maximum error of 0.974 pixels. These results demonstrate that the proposed methods can achieve sub-pixel center detection. The proposed methods also show good stability and strong potential for engineering applications.

Owing to the limited interfacial contact area, insufficient carrier transport efficiency, and the adverse effects of intrinsic defects in ZnO on photoresponse, further improvement in the performance of conventional ZnO/GaN heterojunction ultraviolet photodetectors remains restricted. To address these issues, Ga+Al co-doped ZnO nanorod arrays with different Ga doping concentrations were grown on porous p-GaN/Al₂O₃ substrates by a low-temperature hydrothermal method, and the corresponding Ga+Al co-doped ZnO nanorod/porous GaN heterojunctions were fabricated. The porous p-GaN structure was used to enhance heterojunction interfacial contact and light absorption, while Ga+Al co-doping was employed to regulate the defect states and carrier transport properties of ZnO nanorods, thereby improving the self-powered ultraviolet photodetection performance of the devices. The findings of the study demonstrated that under 365 nm ultraviolet illumination at 0 V bias, the device with a Ga doping concentration of 3 at.% exhibited the best UV photodetection performance, with a light/dark current ratio of 8250, a responsivity (R) of 0.158 A/W, a specific detectivity (D*) of 3.15×10¹² Jones, and an external quantum efficiency (EQE) of 53.5%. This study provides useful theoretical insight and experimental support for the development of next-generation high-performance ZnO/GaN-based heterojunction ultraviolet photodetectors.

The circular swallowtail beams have recently exhibited better autofocusing ability and more tunability compared with low-order Airy or Pearcey catastrophe beams. However our attention is paid to exploring their metasurface generation and dynamics propagation of directional circular swallowtail (DCS) beams carrying power-exponent-phase vortices based on all-dielectric metasurfaces using finite-difference time-domain (FDTD) method, where the directional phase related to launch angles in x- and y- directions is considered. The combined influence of directional and power-exponent phases on dynamics propagation and orbital angular momentum (OAM) of the proposed beams is explored. It is found that their autofocusing positions can be freely adjusted along pre-designed trajectories owing to different launch angles. And rotation behavior and Archimede spiral structure originated from power-exponent phase can be also found during propagation. More importantly, the directional phase associated with launch angles can be regarded as the superposition of spiral spectrum, which can further extend OAM modes to wider multimode states compared with the non-directional cases. The OAM reduction in multiple modes with directional cases is smaller than that in non-directional cases during propagation, which indicates that multimode OAM spectra of our proposed beams provide potential for reducing OAM power attenuation in free-space propagation because the power decay is jointly undertaken by multiple modes rather than a single mode. This work may provide inspiration for guiding or trapping microparticles in three-dimension space as requirement, and for OAM-based optical communication and imaging by the modulation of multi-degrees of freedom associated with directional and power-exponent phases.

Supercontinuum (SC) generated from femtosecond laser filamentation has found extensive applications due to its broadband spectral properties. In this study, we present a novel method to simultaneously improve the spectral coverage and power density of SC. This is realized by combining two-color femtosecond laser injection and multi-filament array arrangement in fused silica. With this method, high spectral power SC is obtained. The spectral power density is above 0.1 mW/nm over a broad wavelength range from approximately 380 nm to 950 nm. We find that both the spectral range and power density of SC are affected by the input power and the intensity ratio between the fundamental and second-harmonic laser pulses. In addition, the spectral fluctuation of the generated SC is measured to be less than 4% within 6 minutes. These results offer a feasible and effective way to enhance the spectral power and coverage of SC sources. They are of great importance for promoting the practical applications of SC.

Objective: This study addresses the difficulty of interpreting and separating multi-source coupling noise in gravitational reference sensors (GRSs) for spaceborne gravitational-wave detection. Methods: A unified acceleration-noise spectrum model is established for Brownian noise, thermal-field coupling, magnetic noise, electrostatic noise, drive-voltage noise, and residual low-frequency noise, with key parameters calibrated against LISA Pathfinder measurements. CNN layers are used to extract local transient features, BiLSTM layers are used to capture long-range temporal dependence, and adaptive spectral subtraction is then applied sequentially by physical noise category. Results: At an input SNR of 10.2 dB, the proposed method achieves a recovery fidelity of 0.9694 and a waveform overlap of 0.9695, outperforming matched filtering, pure CNN, and pure BiLSTM baselines. Across an SNR range from −15 dB to +25 dB, the method shows a slower performance degradation in the negative-SNR regime. Conclusion: Combining physics-guided noise classification with CNN-BiLSTM temporal modeling improves signal recovery under complex GRS noise backgrounds and provides a useful reference for noise budgeting, simulation pipelines, and onboard denoising algorithms in spaceborne gravitational-wave missions.

To address the high sensitivity of thermally induced diopter and the limited stable operating range of near-collimated propagation thin-disk multi-pass amplifiers under high-power and high-energy conditions, this work investigates the suppression of the thermal lensing effect based on pump light intensity distribution control. First, the relationship between thin-disk diopter variation and the pump light intensity distribution is analyzed based on experimental measurements of the thin-disk diopter. On this basis, an M-shaped pumping is proposed to replace the conventional super-Gaussian pumping. A theoretical model is established to comparatively analyze the thin-disk temperature distribution and diopter variation under both pumping techniques within a pump power density range of 0−8.13 kW/cm². The simulation results show that when the super-Gaussian order of the central depression region of the M-shaped pump is 8, the diopter variation of the thin-disk is minimized, with values of 0.00283 m⁻¹ and −0.00455 m⁻¹ in the horizontal and vertical directions, respectively. Compared with the traditional pump with a super-Gaussian order of 10, the diopter variations in the two directions are reduced by 0.05171 m⁻¹ and 0.06355 m⁻¹, corresponding to reductions of 94.7% and 93.3%, respectively. The M-shaped pumping can significantly reduce the thermally induced diopter variation of the thin-disk. This provides more favorable conditions for mode matching over the full pump power density range and substantially mitigates the risk of optical damage caused by pump power fluctuations.

The integration of metasurfaces with optical sensors can effectively reduce the sensor volume and enhance its capability for electromagnetic field manipulation. This paper proposes and fabricates an all-dielectric multifunctional metasurface optical sensor based on a disk-with-double-gap silicon array on a quartz substrate. By introducing two asymmetrically arranged gaps oriented at 45° to break the structural symmetry, the proposed structure successfully converts the non-radiative ideal bound state in the continuum (BIC) into a high-Q quasi-BIC state with strongly localized optical fields, and excites an ultra-narrow linewidth Fano resonance sensing peak at 1617 nm. Simulation results indicate that the resonance peak is predominantly contributed by the magnetic dipole (MD) mode, with a theoretically maximum quality factor (Q) of up to 1.6×1051.6×10⁵ and a figure of merit (FOM) reaching 36350. The sensor exhibits a refractive index sensitivity of 363.5 nm/RIU and a temperature sensitivity of 51.96 pm/°C. Furthermore, the modulation depth of the metasurface resonance peak can be controlled by varying the polarization state of the incident light. Experimental sensing analysis demonstrates a sensitivity of 268.7 nm/RIU for liquids with different refractive indices. This structure holds promise for applications in environmental monitoring, biomedical detection, polarization-controlled optical switching, and provides a reference for multi-parameter metasurface sensors, extending the multifunctionality of metasurfaces in practical sensing applications.

To satisfy the thermal deformation testing requirements of ceramic-based ultra-stable structures for space gravitational wave detection, and address the difficulty of verifying the measurement link prior to component fabrication, a ground-based vacuum interferometric measurement system operating within 1 mHz–0.1 Hz is developed in this paper. We use an equivalent 4J32 Invar sample for tests. It matches ceramic parts in geometry, interfaces and optical path. We calibrate thermal expansion and test displacement stability. We also decompose low-frequency noise systematically. In the experiment, the tested structure, fiber-optic measuring probe, reflector and temperature sensors are placed in a vacuum environment, and the natural cooling of the cavity is utilized to realize the overall thermal response calibration of the measurement link. Under mK-level steady-state temperature control, the Welch method is employed to acquire the amplitude spectral density of displacement noise, and a comparative analysis is conducted on the intrinsic noise of the interferometer, thermal equivalent noise and system comprehensive noise. The experimental results show that the relative deviation between the system comprehensive thermal expansion coefficient and the intrinsic value of Invar is about 8.3%, which can effectively characterize the overall thermal response of the measurement link. The amplitude spectral density of displacement noise of the system in the mHz band is approximately 26.6 nm/√Hz, and the consistency of long-period multi-segment steady-state measurement results is high, demonstrating high reliability. The intrinsic noise of the interferometer is about two orders of magnitude lower than the system comprehensive noise, and the thermal equivalent displacement noise converted from temperature fluctuation only accounts for 7.8%~14.1% of the system noise; both of them are far lower than the comprehensive measurement noise and do not constitute major interference. The proposed system and method complete the full measurement link verification and noise benchmark establishment, and can provide an equivalent verification foundation and reusable technical scheme for subsequent thermal deformation testing of ceramic-based ultra-stable structures.

To meet the demand for multifunctional polarization manipulation and dynamic tunability in terahertz devices, a dual-functional switchable chiral metasurface based on graphene carrier modulation is proposed. By changing the polarization state of the incident wave and continuously tuning the Fermi level of graphene through an external gate voltage, the structure can exhibit circular dichroism (CD) and linear dichroism (LD) responses, enabling switching between different polarization-selective absorption characteristics. Simulation results show that when the graphene Fermi level is 1 eV, the metasurface exhibits pronounced selective absorption for left- and right-handed circularly polarized waves at 2.65 THz, with a CD value reaching 0.89, and maintaining CD values above 0.6 within the frequency range of 1.97–3.44 THz. When the Fermi level decreases to 0.2 eV, a significant linear dichroism response appears at 1.91 THz, with an LD value of 0.75. Analysis of the electric field and surface current distributions reveals that the difference in the strength of electric resonances excited under different polarization states is the primary mechanism responsible for polarization-selective absorption. In addition, the proposed structure demonstrates good robustness against variations in the incident angle and structural parameters, indicating its potential applications in circular/linear dichroism detection, polarization control, and terahertz photonic devices.

To address the issues of insufficient adaptability in cross-view feature fusion and inadequate utilization of complementary information in existing dual-view X-ray security inspection image prohibited item detection methods, this paper proposes an improved dual-view fusion detection method combined with YOLOv11 (Dual View Fusion combined with YOLOv11, DVF-YOLOv11). The proposed method employs a parameter-shared dual-branch YOLOv11 backbone network to extract multi-scale features from the overlook-view and side-view images, respectively. A Cross-View Attention Fusion (CVAF) module is designed to adaptively enhance dual-view features through a cascaded mechanism of channel attention and spatial attention. An adaptive weight prediction network is introduced to dynamically adjust the fusion weights of each view, and is combined with channel compression convolution to form a dual-path fusion strategy. A joint loss function composed of feature preservation loss, complementarity loss, and weight balance loss is further designed to guide the fusion learning process. On the DvXray dataset, the proposed method achieves an mAP50 of 94.02% and an mAP50-95 of 79.41%, improving by 2.99% and 5.29%, respectively, over the single overlook-view baseline. Experimental results demonstrate that the proposed method improves the accuracy and robustness of prohibited item detection in dual-view X-ray security inspection images.

Objective: The magnetic field near the test masses in space-based gravitational-wave detection spacecraft cannot be measured in situ, and the accuracy of magnetic field reconstruction is strongly affected by the arrangement of magnetic sensors. To address this issue, this study investigates a magnetic sensor configuration optimization method under constrained installation conditions, aiming to improve the magnetic field reconstruction accuracy at the test mass locations. Methods: The magnetic sensor placement problem was formulated as a discrete combinatorial optimization problem. An improved Ivy algorithm-based magnetic sensor configuration optimization method, termed MSC-IVYA, was proposed. The method integrates feasible installation region discretization, default-configuration-based population initialization, dynamic neighborhood updating, and a cumulative fitness function designed for multiple random magnetic source models, thereby enabling efficient search under installation constraints. Simulation evaluations were conducted on two representative space-based gravitational-wave detectors, LISA Pathfinder and Taiji-2, using three magnetic field reconstruction methods: inverse distance weighting (IDW), Taylor expansion (TE), and multipole expansion (ME). Results: For LISA Pathfinder, under the default configuration, the average relative errors of TM1 were 593.74%, 508.04%, and 516.50% using IDW, ME, and TE, respectively. After optimization with MSC-IVYA, these errors were reduced to 390.39%, 357.55%, and 363.89%, respectively. In the Taiji-2 case, MSC-IVYA also achieved consistent improvement. For TM1, the reconstruction errors using IDW and ME decreased from 72.14% and 77.27% to 32.55% and 47.25%, respectively. For TM2, the errors using ME and TE decreased from 97.17% and 112.14% to 74.27% and 80.76%, respectively. Conclusion: Magnetic sensor configuration is an important design variable affecting the magnetic field reconstruction performance at the test mass locations. The proposed MSC-IVYA method can consistently improve magnetic field reconstruction accuracy under different mission conditions. It is particularly suitable for engineering scenarios with a limited number of magnetic sensors and constrained installation regions, and provides methodological support for the design of magnetic diagnostic systems in space-based gravitational-wave detection spacecraft.

To overcome the limitations of current technologies, including the slow switching speed, heat accumulation, and high power consumption of thermo-optic waveguide switches, the high transmission loss of electro-optic waveguide switches, and the complex feedback control, difficulty in large-scale array integration, and narrow operating bandwidth commonly found in traditional photonic integrated circuit (PIC) waveguide switches, to meet the future demands of on-chip all-optical switching technologies for optical switches with fast response, low power consumption, broad bandwidth, low cost, and large-scale array fabrication capabilities, this study investigates micro-electro-mechanical systems (MEMS) driven silicon-based waveguide optical switch devices. By integrating silicon photonic waveguide technology with MEMS technology, we designed and fabricated an electrostatically driven MEMS 2×2 silicon waveguide optical switch (silicon photonic MEMS switch) capable of routing optical signals. The monolithic integration of silicon photonic waveguides and MEMS microactuators on a silicon wafer was achieved using electron-beam lithography combined with complementary metal-oxide-semiconductor (CMOS) processes. With a footprint of 192 μm × 192 μm, the device successfully demonstrated 2×2 optical switching functionality. The switching response times were measured at 20 μs and 15 μs, with optical signal rise and fall times of 15 μs and 10 μs, respectively. At a wavelength of 1550 nm, the device achieved an extinction ratio (ER) of 35 dB and an insertion loss (IL) of −0.8 dB. Over the 1500–1600 nm wavelength band, the ER remained above 20 dB, and the holding power consumption in the ON state was less than 0.5 μW. Experimental results demonstrate that this silicon photonic MEMS optical switch features fast response, low modulation power consumption, and excellent broadband performance. Furthermore, it can be fabricated into large-scale arrays with simple control mechanisms using existing process platforms, indicating significant application potential in future on-chip all-optical switching networks.

For ultrashort laser pulses, accurately characterizing their temporal characteristics (temporal width and phase) is crucial for their generation and application. Self-referenced spectral interferometry (SRSI), first proposed in 2010, utilizes the measured light itself to generate suitable reference light through third-order nonlinear optical processes, and employs Fourier transform spectral interferometry algorithms to reconstruct the input pulse. It has the advantages of single-shot, accuracy, and high sensitivity. This article provides an overview of the implementation of SRSI from two main aspects: the optical path and the reconstruction algorithm. On the optical path level, from the earliest proposed self-referenced spectral interferometry based on cross-polarization wave generation (XPW-SRSI) to the self-referenced spectral interferometry based on transient grating effect (TG-SRSI) with a compact total reflection configuration, the sensitivity, wavelength coverage, and compactness of the implementation path have been continuously iteratively upgraded. On the algorithm level, from pulse reconstruction methods targeting near Fourier transform limits to reconstruction algorithms for large chirp pulses with temporal broadening exceeding twice the Fourier transform limit, three evolutionary paths are discussed: spectral stitching schemes, reconstruction schemes incorporating supervised deep learning, and neural networks without training embedded in physical forward models. The latter achieves single-shot accurate reconstruction in large chirp and high noise scenarios without any pre-training dataset. In the face of emerging new beam characterization demands, the temporal measurement of ultrashort laser pulses still require significant attention in the future.

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.

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.

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.

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.

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.

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.

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.