Restoration of phase aberrations is crucial for addressing atmospheric turbulence in light propagation. Traditional restoration algorithms based on Zernike polynomials (ZPs) often encounter challenges related to high computational complexity and insufficient capture of high-frequency phase aberration components, so we proposed a Principal-Component-Analysis-based method for representing phase aberrations. This paper discusses factors influencing the accuracy of restoration using Principal Components (PCs), mainly sample space size and the sampling interval of D/r₀, which is used to characterize the strength, with r₀ being the atmospheric coherence length and D being the pupil diameter, on the basis of characterizing phase aberrations by PCs. The experimental results show that a larger D/r₀ sampling interval can ensure the generalization ability and robustness of the principal components in the case of a limited amount of original data, which can help to achieve high-precision deployment of the model in practical applications quickly. In the environment with relatively strong turbulence in the test set of D/r₀ = 24, the use of 34 terms of PCs can improve the corrected Strehl ratio (SR) from 0.007 to 0.1585, while the Strehl ratio of the light spot after restoration using 34 terms of ZPs is only 0.0215, demonstrating almost no correction effect. The results indicate that PCs can serve as a better alternative in representing and restoring the characteristics of atmospheric turbulence induced phase aberrations. These findings pave the way to use PCs of phase aberrations with fewer terms than traditional ZPs to achieve data dimensionality reduction, and offer a reference to accelerate and stabilize the model and deep learning based adaptive optics correction.

The counter-rotating prisms atmospheric dispersion corrector (ADC) has been widely used for the calibration of large-aperture astronomical telescopes. To achieve an optimal design method for the counter-rotating prism ADC, effectively compensate for atmospheric dispersion, and suppress the optical axis drift introduced by the ADC, we establish a vector model for ray tracing of the counter-rotating prism ADC based on traditional atmospheric dispersion compensation theory. The vector models of dispersion compensation and optical axis drift are then derived. Using this mathematical model, the impacts of different parameters of the ADCs on the dispersion compensation effect, prism rotation angle, and optical axis drift are simulated and analyzed. The simulation results show that when compensating for the same atmospheric dispersion by using the counterrotating ADC with different material combinations and bonding types, the rotation angle of the prism group remains relatively consistent, and the differences increasing as the zenith angle increases. Choosing materials with similar refractive indices near the central wavelength reduces chromatic aberration in the ADC output light and improves dispersion compensation performance. When compensating for atmospheric dispersion at different zenith angles, the offset angle of the system's optical axis decreases as the number of bonded surfaces increases. Specifically, each additional bonded surface the optical axis drift angle can be reduced by one order of magnitude. In practical ADC design, dispersion can be effectively compensated, and optical axis drift can be suppressed by controlling the number of bonded surfaces and material selection.

A metal-sensitive diaphragm fiber optic pressure sensor with temperature compensation is proposed to address pressure monitoring in high-temperature environments, such as engine fuel systems, oil and gas wells, and aviation hydraulic systems. The sensor combines a metal-sensitive diaphragm and a sapphire wafer to form a temperature-pressure dual Fabry-Perot (FP) interference cavity. A cross-correlation signal demodulation algorithm and a temperature decoupling method are utilized to reduce the influence of temperature crosstalk on pressure measurement. Experimental results show that the maximum nonlinear error of the accuracy of the sensor pressure measurement is 0.75% FS and 0.99% FS at room temperature and 300 °C, respectively, in a pressure range of 0−10 MPa and 0−1.5 MPa. The sensor’s pressure measurement accuracy is 1.7% full scale (FS) when using the temperature decoupling method. The sensor exhibits good static pressure characteristics, stability, and reliability, providing an effective solution for high-temperature pressure monitoring applications.

As a potential alternative for energy in quantum regime, a quantum battery inevitably undergoes the process where the extracted work deteriorates due to the environmental decoherence. To inhibit the energy dissipation, we have put forward a scheme of a moving atom battery in a lossy cavity coupled to a structured environment. We investigate the dynamics of the maximally extracted work called the ergotropy by the open quantum system approach. It is found out that the decay of quantum work is significantly retarded in the non-Markovian environment. In contrast to the static case, the storage performance of the quantum battery is improved when the atom is in motion. The effect of energy preservation becomes more pronounced at higher velocities. Both the momery effect and motion control can play a positive role in extending the discharge lifetime. In addition, we have investigated the effects of environmental temperature, random noises, and quantum entanglement. These present results provides a feasible protocol for the open quantum battery.

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.

In order to achieve real-time 3D measurement of dynamic objects and to overcome the measurement accuracy limitations caused by spectral aliasing of different carrier frequencies in traditional Fourier demodulation methods, as well as the color coupling problem in color composite stripe projection techniques, this paper proposes a three-frequency color stripe projection profilometry method based on fast iterative filtering. The method first captures a color image using a CCD camera, where the red, green, and blue channels carry gray stripe images with different carrier frequencies. Background interference is then reduced by component subtraction, followed by carrier frequency separation and color decoupling using fast iterative filtering. The subsequent application of the Fourier transform is applied to the carrier-frequency stripe images in the red, green, and blue channels enables the extraction of wrapped phase information. To achieve accurate phase unwrapping, a spatial domain unwrapping algorithm is employed. The low-frequency phase is first unwrapped, followed by the middle and high-frequency phases, which are unwrapped sequentially to complete the entire phase unwrapping process. The simulation and experimental results demonstrates that the proposed method exhibits a phase unwrapping accuracy that is 7 times higher than that of traditional Fourier methods. In comparison with other single-frame demodulation methods, the proposed method demonstrates superior accuracy and robust noise resistance, thus providing an effective technical solution for high-precision, dynamic real-time 3D measurement.

The purpose of this study is to solve the problem of optical waveguide shape defects. These defects occur during the process of vertical end face waveguide bridging in photonic chips. The obstruction of the laser beam by the surface of the chip is the root cause of these defects. The present study investigates the light intensity distribution based on the focusing light field of high numerical aperture (NA) lenses. The study focuses on the laser focus at different x-direction offsets on the vertical end-face of the chip. First, we give the analytical expressions of the light field near the focus. These are in the focusing system of high NA lenses. In addition, we give the expressions for the focused light field components. This analysis is conducted under the assumption of linearly polarized light incident. We then conduct numerical simulations with the given expressions. We study the focal light intensity distribution at different offsets in the x-direction. These offsets are measured from the vertical end face of the photonic chip. The intensity changes resulting from the disturbance of the focal light field are presented. The focal light field intensity changes are drawn. These curves are then compared with the trend of the waveguide shape changes in the experiments. Finally, based on the focal light intensity distribution curves, the reverse curves of the laser power compensation coefficients are derived. These are then applied to the optical waveguide compensation processing experiments. After power compensation processing, the parts with waveguide width less than 4 μm. Following this compensation, these components are successfully adjusted to a width of 4 μm, resulting in a straighter shape. The defects are effectively repaired. This finding is corroborated by both numerical simulations and experimental results. This method has been demonstrated to be an effective means of compensating for defects in waveguide shape. These defects are attributed to insufficient laser power. This method provides an effective solution for waveguide processing in photonic chip integration.

Objective: Aiming at the problem that the diffraction phenomenon generated in the Long-Wave Infrared (LWIR) polarized optics system containing Digital Micro-mirror Device (DMD) will lead to the change of the polarization aberration in the system, which will cause a decrease in the accuracy of the polarization measurement of the LWIR polarized optics system, we propose a method for analyzing and compensating for the polarization aberration of the LWIR secondary imaging optical system containing DMD. Method: Firstly, a diffraction and polarization aberration characteristic transmission model is constructed for the relationship between wavelength and DMD size in the LWIR polarized optics system, and a polarization aberration analysis method based on the Jones vector theory of vector diffraction-polarized light is proposed. Secondly, the polarization aberration and polarizability of DMD are deduced to determine the optimal diffraction order, incidence angle and diffraction efficiency of DMD, and then the secondary imaging LWIR polarized optics system containing DMD is designed to obtain the influence of DMD diffraction characteristics on polarization aberration. Finally, the polarization aberration of the optical system is compensated by tilting the projection objective, coating the lens and reducing the surface incidence angle, so as to solve the influence of diffraction phenomenon on the polarization aberration of the LWIR polarized optical system. Result: Simulation results show that the full-field-of-view modulation transfer function of the system is close to the diffraction limit at the cut-off frequency, the maximum aberration is less than 0.2%, the imaging quality is good, and the two-way attenuation of the whole system is reduced to 1/12 of the original one after compensation. Conclusion: This analytical model can reveal the relationship between diffraction and polarization aberration, and the compensation method can effectively reduce the polarization aberration.

In order to quantitatively assess the solar stray light suppression capability of the heliospheric imager, a testing approach and experimental validation of the solar stray light suppression capability of the heliospheric imager were investigated. In this paper, we propose a method to test the solar stray light suppression capability of the heliospheric imager under laboratory circumstances by conducting segmented tests of the front-end baffle and the camera. This approach circumvented the issue that the structural scattering caused by the test under vacuum conditions would be overly large and influence the accuracy of the test results. The proposed method was then employed to assess the effectiveness of a heliospheric imager in suppressing solar stray light under laboratory conditions. The experimental results indicated that the PST of the heliospheric imager was 1.4×10⁻⁸ at WACH1 and 4.3×10⁻⁹ at WACH2. The error analysis of the test results revealed that the random error was 21.6%, and the PST resulting from the sum of system errors was 1.1×10⁻⁸ at WACH1 and 4.2×10⁻⁹ at WACH2. The test accuracy met the requirements, demonstrating the feasibility and accuracy of the test method. The study presented in this paper offers a novel means to test the solar stray light suppression capability of heliospheric imager.

Most of the current visual training products available on the market use electronic screens to display objects of varying dimensions and distances, thereby stimulating the ciliary muscle through looking at the screen for visual function training. However, this method involves blue light radiation, which poses a potential hazard to the human eye. To address this issue, a visual optical system based on a Varifocal zoom structure has been designed. The system achieves continuous magnification of optical power by manipulating the lateral movement of two sets of lenses perpendicular to the optical axis. This simulates changes in object distance and stimulating ciliary muscle regulation training. This paper first derives the surface shape limits of variable focal length lenses, incorporates the variable focal length spherical effect equation to optimize the basic surface shape of Alvarez lenses, and uses Zemax software for design. The designed lens surface is characterized by a third-order XY polynomial free-form surface, with a maximum relative vertical axis offset of 5.6 mm between the two groups of lenses, achieving continuous magnification of refractive power between +4D and −8D. The design results indicate that the full-field modulation transfer function exceeds 0.3 at a Nyquist frequency of 30lp/mm, with root mean square (RMS) radius values approaching the Airy spot radius value and distortion below 2%. The imaging quality of this optical system is satisfactory.

In this paper, a method for vortex beam OAM detection using crosshair diffraction is proposed. The OAM-related main bright spot in the far-field distribution contains most of the energy of the incident beam (50%~84%) and there is no secondary bright spot that interferes with the detection. In contrast, the energy proportion of the main bright spot in the conventional small-hole diffraction method is extremely low, particularly in the far-field main bright spot above the 7th-order topological charge, which contains less than 1% of the energy of the incident beam. Furthermore, as the topological charge level increases, the secondary bright spot becomes more intrusive. Consequently, crosshair measurements are particularly applicable to the detection of weak vortex beams, which has potentially important implications for the development of long-range free-space optical communications.

A new type of 785 nm semiconductor laser device has been proposed. The thin cladding and mode expansion layer structure incorporated into the epitaxy on the p-side significantly impacts the regulation of grating etching depth. Thinning of the P-side waveguide layer makes the light field bias to the N-side cladding layer. By coordinating the confinement effect of the cladding layer, the light confinement factor on the p-side is regulated. On the other hand, the introduction of a mode expansion layer facilitates the expansion of the mode profile on the P side cladding layer. Both these factors contribute positively to reducing the grating etching depth. Compared to the reported epitaxial structures of symmetric waveguides, the new structure significantly reduces the etching depth of the grating while ensuring adequate reflection intensity and maintaining resonance. Moreover, to improve the output performance of the device, a new epitaxial structure has been optimized. Based on the traditional epitaxial structure, an energy release layer and an electron blocking layer are added to improve the electronic recombination efficiency. This improved structure has an output performance comparable to that of a symmetric waveguide, despite being able to have a smaller gain area.

To improve the processing efficiency of large-aperture optical components, a multi-robot, multi-tool collaborative processing method was proposed. A collaborative layout that has been tailored to the optical components was designed, and three feasible trajectories were simulated for analysis. The discrete simulation results were then used to establish principles for selecting trajectory parameters. To address the limitation of discrete simulation in capturing the influence of trajectory continuity on the surface map, an integral removal function model adapted to the motion mode was introduced. Furthermore, a collaborative machining obstacle avoidance strategy was developed. The experimental results obtained using the optimal trajectory demonstrated that with an initial surface shape of PV=18.310λ (λ=632.8 nm) and RMS=1.788λ, the final surface achieved PV=4.873λ and RMS=1.113λ. In addition, within the effective range of 120 mm diameter, PV=4.661 λ, RMS=0.857λ, converged to PV=2.465λ and RMS=0.622λ after processing. The total execution time was 3.943 hours, with the maximum execution time for a single processing unit being 2.041 hours, representing a 1.93-fold improvement over single-tool processing. This method significantly enhances processing efficiency, ensures surface shape accuracy, and holds great potential for the manufacturing of large-aperture optical components.

The Bi₂O₃/Bi₂S₃ heterojunction composite was prepared by thermal polymerization combined with room temperature solution method, and its micromorphology, crystal structure and elemental composition were characterized. The results demonstrate that the Bi₂O₃/Bi₂S₃ heterojunction composite exhibits a bulk morphology, accompanied by the presence of pores and a relatively rough surface. Based on the Bi₂O₃/Bi₂S₃ heterojunction composite, the photodetector was fabricated and its photodetection performance was measured under zero bias voltage. When exposed to ultraviolet (UV) light, the maximum photocurrent (0.32 μA) and response speed (65.65/80.56 ms) of the Bi₂O₃/Bi₂S₃ photodetector are significantly enhanced compared to those of the Bi₂O₃ photodetector. In addition, the device exhibits a wide photodetection band from the ultraviolet (UV) to the visible (Vis) spectrum, as well as fast and stable self-driven photodetection capability. This is mainly attributed the successful coupling of Bi₂O₃ and Bi₂S₃ with a narrow band gap, resulting in the formation of a heterojunction composite that exhibits a type II band structure. It is noteworthy that the photodetection performance of the device was measured by continuously alternating between blue light on and off for 100 times. This indicates that the Bi₂O₃/Bi₂S₃ photodetector exhibits excellent cycle stability.

A folding off-axis three mirror telescope has been used as the common optical path component in the design of an optical system suitable for a new airborne multispectral common aperture targeting pod. The optical system is characterized by miniaturization, high transmittance, multispectral, long focal length, and low difficulty of installation and adjustment. The designed multispectral common aperture optical system has an effective optical aperture of 220 mm, a near-infrared focal length of 1100 mm, a short-wave infrared focal length of 1200 mm, and a medium-wave infrared focal length of 880 mm. It can be integrated as a transmitting and receiving antenna with a laser sensor, which shares the same aperture and fast steering mirror with other imaging sensors. The system is mounted on a typical airborne spherical electro-optical pod platform with a diameter of 500 mm. The optical design analysis and results indicate that the image quality of the optical design has reached the diffraction limit. All indicators and parameters meet the technical requirements.

With the wide application of holographic head-up display system and virtual reality augmented display technology, holographic reproduced images are required to be virtual images with higher quality, more realistic reproduction image size and more in line with human visual characteristics. Based on the principle of computer-generated holograms reproduction imaging, this paper used the Gerchberg-Saxton (GS) algorithm to iteratively solve the phase distribution of the original simulation images under different characteristic parameters (line width, ring diameter) and different calculated sampling intervals by performing direct and inverse Fourier transforms on the optical field distributions of the input and output planes, and the corresponding reproduced images were obtained by simulation calculation. The optical path of the holographic reproduction experiment was constructed by using the liquid crystal spatial light modulator, and the reproduction experiment was carried out by loading the phase distribution maps of different original simulation images, the holographic reproduction images of far-field diffraction were taken by the camera, and the actual feature size of the reproduced images was obtained by image processing. The experimental results show that the feature size of the reproduced images is basically linear with the characteristic size of the original simulation images. Furthermore, the reproduction image size shows a non-linear change relationship with the sampling intervals of the simulation calculation, which is consistent with the derived theoretical calculation relationship curve. In order to further verify the correctness of the conclusion, when the size of the expected reproduced image is designed as the ring diameter of 0.943mm and the line width of the central cross of 0.015mm. The characteristic size and sampling interval of the original simulation image of the expected target are obtained by the simulation calculation as the line width of 3pixel, the ring diameter of 594pixel and the sampling interval of 25μm, respectively. The ring diameter and line width of the holographic reproduction image, as measured by the reproduction experiment, are 0.93mm and 0.017mm, respectively. The error accuracy is within 0.02mm. The findings of this study provide an effective reference for application scenarios such as holographic display and AR/VR display to improve the authenticity of virtual display image size.

Diffractive waveguide, known for their lightweight, wide field of view, and large eyebox, have emerged as one of the most promising solutions for augmented reality (AR) near-eye display technologies. However, most commercially available AR waveguide simulation software is developed by foreign companies, and domestic advancements in 3D visualization software for optical waveguide design and simulation remain notably absent. To our knowledge, this work introduces the first domestically developed 3D visualization module for optical waveguide design and simulation based on ray-field tracing. Using this module, we engineered a two-dimensional exit-pupil-expansion diffractive waveguide, demonstrating a systematic design workflow. The workflow integrates k-domain analysis, automated layout generation of grating regions within the optical waveguide, waveguide optimization, and ray-field tracing simulations, establishing a cohesive methodology for device development. The module extends beyond single-waveguide simulations to system-level analyses of near-eye displays, incorporating micro-dislplays, micro-projectors, and human eye models. By bridging microscopic and macroscopic scales, it enables holistic performance evaluation of AR optical systems, highlighting its capabilities and technical advantages. This module provides a robust and efficient platform for domestic optical engineers to advance optical waveguide design and simulation, thereby accelerating the industrialization and technological progression of AR optics in our country.

This paper investigates optical transport in metamaterial waveguide arrays (MMWAs) exhibiting Bloch-like oscillations (BLOs). The MMWAs is fabricated by laterally combining metal and dielectric layers in a Fibonacci sequence. By mapping the field distribution of Gaussian wave packets in these arrays, we directly visualize the mechanical evolution in a classical wave environment. Three distinct oscillation modes are observed at different incident positions in the ninth-generation Fibonacci structure, without introducing thickness or refractive index gradient in any layer. Additionally, the propagation period of BLOs increases with a redshift of the incident wavelength for both ninth- and tenth-generation Fibonacci MMWAs. These findings provide a valuable method for manipulating BLOs and offer new insights into optical transport in metamaterials, with potential applications in optical device and wave control technologies.

Atmospheric coherence length is a critical indicator of the impact of atmospheric turbulence on free-space optical communication links. This paper proposes a novel strategy for measuring atmospheric coherence length by utilizing extended targets as the information source. Specifically, the method integrates the wavefront structure function approach with the extended target offset algorithm to directly estimate the atmospheric coherence length. Traditional methods, such as the Differential Image Motion Monitor (DIMM), typically rely on guide star targets, which are difficult to set appropriately in horizontal communication links, thereby limiting their effectiveness in practical applications. In contrast, employing extended targets as direct detection targets provides a feasible solution for measuring atmospheric coherence length. The paper first reviews the principles and current research status of mainstream algorithms, emphasizing the reliance of existing algorithms on guide star targets and their limitations in horizontal links. Subsequently, we propose a new measurement scheme that combines the improved normalized cross-correlation algorithm with the wavefront structure function method to estimate atmospheric coherence length under extended targets scenarios. In comparison to traditional measurement methods, our approach enables coherence length measurement based on extended targets in horizontal links, thereby significantly reducing system complexity and equipment costs. To validate the effectiveness and measurement accuracy of the proposed method, both simulations and experiments were designed and conducted. The results demonstrate that the coherence length values measured by this method are highly consistent with those obtained using the DIMM method and the wavefront phase variance method, with a measurement accuracy error of approximately 4%. This indicates that the proposed method can effectively assess atmospheric coherence length, thereby providing a valuable reference for enhancing the reliability of free-space laser communication systems.

Division of Focal Plane (DoFP) polarization camera is a widely used integrated polarization imaging system. Crosstalk between pixels of Micro-Polarizer Arrays (MPAs) is a unique interference factor in such system, and its intensity varies with the polarization characteristics of incident light, thereby introducing errors into the measurement of the target's polarization information. This paper reviews the development of polarization crosstalk models and summarizes the factors affecting crosstalk identified in relevant research. Focusing on sensor parameters and optical system parameters as key factors, this study discusses the cause-effect model of crosstalk in cameras and its relation to temporal noise. It analyzes the results of the parameter changes caused by crosstalk, primarily summarizing the crosstalk's factor correlation, experimental repeatability, error randomness, and parameter calibration. Finally, this study prospects the future development trends of crosstalk models.

To achieve wide-area detection of space targets, this study designs an optical system design with a broad spectrum range (400 nm−1000 nm), a large field of view (61°), a small F-number (1.38), and low distortion. This optical system is capable of detecting space targets with a magnitude of 6, enabling wide-area detection. Initially, a mapping between the radiation model of space target detection and the optical system parameters is established. The optical design is then theoretically analyzed using a reverse telephoto layout as the starting point. The design is optimized to balance and correct severe chromatic aberration resulting from the large field of view and wide spectral range, while improving enclosed energy and considering the roundness of scattered spots. The detection capability is verified through space optical simulation experiments. Results show that the optical system meets the wide-area detection requirements for space targets with a magnitude of 6. Finally, the physical detection capability of the optical system is experimentally verified. The results indicate that the optical system is capable of wide-area detection of space targets with a magnitude of 6. The overall design of the optical system is reasonable and compact, meeting the requirements of wide-area detection of space targets.

With the rapid development of bioluminescence technology, the demand for high-precision signal transmission has increased significantly. The spectral characteristic of the filter film, as the core component of the system, directly affects the accuracy of signal transmission. In this study, Nb₂O₅ and SiO₂ were selected as high and low refractive index materials, respectively. A multi-channel negative filter was optimized using the Gaussian apodization function and Optilayer software. The filter film was deposited on a D263T substrate using an inductively coupled magnetron sputtering technique. The effect of thickness control errors on spectral shift and passband transmittance was addressed through inverse film sensitivity analysis. The effect of process parameters on film roughness was investigated, and it was found that adjusting the ICP power could effectively improve film roughness. When the developed multi-channel negative filter was tested at a 45° angle of incidence, the reflectance half-bandwidths of the center wavelengths of 576 nm, 639 nm, and 690 nm were 5 nm, 6 nm and 7 nm, respectively, with an average reflectance of about 98%. The average transmittance in the transmission ranges of 545−562 nm, 597−624 nm, 655−675 nm, and 708−755 nm was 92%. The multi-channel negative filter successfully passed both the environmental resistance test and the spectral stability test, thus meeting the application requirements of the multi-channel negative filter in the bioluminescence system.

Compared to traditional single-frequency bound states in the continuum (BIC), dual-band BIC offers higher degrees of freedom and functionality. Therefore, implementing independent control of dual-band BICs can further enhance their advantages and maximize their performance. This study presents a design for a dielectric metasurface that achieves dual-band BICs in the terahertz (THz) range. By adjusting two asymmetry parameters of the structure, independent control of the two symmetry-protected BICs is achieved. Furthermore, by varying the shape of the silicon holes, the design's robustness to geometric variations is demonstrated. Finally, the test results show that the figures of merit (FOMs) for both BICs reach 10⁹. This work provides a new approach for realizing and tuning dual-frequency BICs, offering expanded possibilities for applications in multimode lasers, nonlinear optics, multi-channel filtering, and optical sensing.

Organic-inorganic hybrid lead-free perovskites have garnered significant attention due to their non-biotoxicity and environmental sustainability. Among these materials, MA₃Sb₂I₉, with its stable zero-dimensional (0D) structure and lead-free nature, shows great promise for stable and efficient photodetection applications. In this study, we employ a MACl post-treatment to enhance the quality of MA₃Sb₂I₉ perovskite thin films fabricated through antisolvent processing. This treatment facilitated the formation of Cl-Sb bond interactions between MACl and the perovskite thin films, effectively passivating the I⁻ vacancies and grain boundary defects on the MA₃Sb₂I₉ thin-film surface. This process not only improve the surface morphology and crystallinity of the thin film but also reduced the defect states density of the surface, thereby enhancing carrier extraction and transport efficiency. Consequently, the sensitivity of self-powered photodetectors based on the optimized thin-film preparation increased from 3.89 × 10⁷ Jones to 5.72 × 10⁸ Jones, representing an improvement by one order of magnitude. Furthermore, the rise and fall times were shortened from 37/76 ms to 31/37 ms, respectively, indicating an enhancement in the response speed of the devices.

Stripe projection technology is widely used in 3D measurement and surface morphology reconstruction, where phase quality is a critical determinant of measurement accuracy. However, the nonlinear relationship between input and output light intensity is a major source of phase error. To address this issue, this paper introduces a novel system nonlinear active correction method. This method captures the variation pattern between input and output light intensity by projecting a small number of uniform gray-scale images onto a standard plane. This pattern is then integrated with active system nonlinear correction to construct a system nonlinear model based on the input-output light intensity variation. Genetic algorithms are used to optimize the coding values, which are then used to actively correct the projected fringes via fringe coding. The corrected fringes effectively reduce the influence of nonlinear effects, thereby significantly improving the quality of phase acquisition. To validate the proposed method, computer simulations were performed using three-step phase shifting. The results showed an 88% reduction in the standard error and an 85.5% reduction in the maximum error. In actual standard plane experiments, the corrected standard phase error decreased from 0.0706 rad to 0.0168 rad, and the maximum phase error decreased from 0.4129 rad to 0.0960 rad. In the face plaster model experiments, the corrected standard phase error decreased from 0.0472 rad to 0.0102 rad, and the maximum phase error decreased from 0.2990 rad to 0.2408 rad. In 3D reconstruction of complex morphology plaster models of human faces, the surface quality was significantly improved, and the water ripple effect, which affects the phase quality, was significantly reduced. Compared with existing large-step phase-shifting methods, the proposed method not only achieves high-quality phase acquisition accuracy, but also offers clear advantages in terms of required data volume and operational convenience, demonstrating broad application potential.

In comparison with traditional photoelectric displacement measurement technologies, displacement measurement methods based on digital image processing methods exhibit superior fault tolerance and flexibility, making them a current research hotspot. To achieve high-precision and high-reliability angular displacement measurement, an image-based angular displacement measurement system based on Manchester coding is proposed. First, a single code-channel raster code disc was designed using Manchester coding based on M-sequence pseudo-random coding. A digital image sensor was then used to construct an optical path for capturing patterns on the raster code disc. Subsequently, a decoding recognition algorithm tailored to the coded patterns was developed. Additionally, edge positioning and sub-pixel subdivision algorithms for coded marker edge pattern fitting were proposed to further enhance the system’s resolution. The proposed method was then experimentally validated. The experimental results demonstrated that the system achieved a resolving power of 21 bits and an accuracy of 1.73 arcseconds with a 100 mm grating code disc. This research provides a foundation for the development of highly reliable and high-performance photoelectric angular displacement measurement technologies. Image-based angular displacement measurement system based on Manchester coding

Terahertz molecular fingerprinting is a promising method for label-free detection, particularly for micro or trace amount samples in practical applications. However, the wavelength of terahertz waves is much larger than the size of the molecules to be tested, resulting in a weak interaction between the waves and the matter. To address this challenge, additional structures are needed to enhance the absorption of electromagnetic waves by trace amount samples. In this study, we constructed an inverted asymmetric dielectric grating structure on a metal substrate. By utilizing guided-mode resonance (GMR) and a bound state in the continuum (BIC) effect, the terahertz absorption spectrum of thin film samples was significantly enhanced. The enhanced absorption spectra can be easily obtained by measuring the reflected absorption signal. The samples are coated on the flat back of the inverted dielectric grating, which simplifies the preparation process. For instance, when the thickness of an α-lactose film is 0.2 μm, the absorption enhancement factor reaches 236. This study provides a new method for detecting trace analytes in the terahertz band.

Multiple functional metasurfaces with high information capacity have attracted considerable attention from researchers. This study proposes a 2-bit tunable decoupled coded metasurface designed for the terahertz band, which utilizes the tunable properties of Dirac semimetals (DSM) to create a novel multilayer structure. By incorporating both geometric and propagating phases into the metasurface design, we can effectively control the electromagnetic wave. When the Fermi energy level of the DSM is set at 6 meV with 80 meV, the electromagnetic wave is manipulated by the DSM patch with the gold patch embedded in the DSM film, operating at a frequency of 1.3 THz and 1.4 THz. Both modes enable independent control of beam splitting under left-rotating circularly polarized (LCP) and right-rotating circularly polarized (RCP) wave excitation, resulting in the generation of vortex beams with distinct orbital angular momentum (OAM) modes. The findings of this study hold significant potential for enhancing information capacity and polarization multiplexing techniques in wireless communications.

In order to solve the problem of RF discharge impedance matching of high-power fast axial flow CO₂ lasers, an impedance matching network with low reflectivity and high dynamic matching range was designed to realize the efficient utilization of RF excited fast axial flow CO₂ lasers under different discharge structures. Based on the impedance matching theory of RF circuits, a multi-electrode equivalent circuit model was constructed, a method of introducing tunable high-voltage ceramic capacitors into the matching network was proposed, and a dynamic L-type matching network suitable for high-power RF excited fast axial flow CO₂ lasers was designed. The simulated dynamic L-type matching network can inject 60 kW RF power into 16 discharge tubes and achieve a reflectivity of less than 1% in the range of total load impedance of 12.81 Ω~49.94 Ω. A single-tube RF discharge experimental device was built, and the reflectivity of the dynamic L-type matching network was measured as less than 1% at 4 kW injection power, which was consistent with the simulation results. It is proved that the dynamic L-type matching network with adjustable high-voltage ceramic capacitors can achieve impedance matching in the high dynamic range, which meets the design requirements of high-power RF excited fast axial flow CO₂ laser matching circuits.

Microdefects in cavity mirrors utilized in cavity ring-down spectroscopy (CRDS) adversely affect measurement accuracy. This paper establishes a microdefect scattering model grounded in Bobbert and Vlieger's Bidirectional Reflectance Distribution Function (BRDF) theory to analyze the characteristics of scattered light from microdefects under varying wavelengths, incident angles, defect sizes, types, densities, and substrate coatings. Studying the cavity mirror microdefect scattering model shows that defects in the micrometer to submicron range (100 um to 0.1 um) affect the ring-down absorption accuracy. Aiming at detecting microdefects of this order, this paper’s authors constructed analytical models of microdefect scattering and dark field detection of microdefects in cavity mirrors. Establishing and analyzing the scattering light model of CRDS mirror microdefects is critical to realizing the high-precision detection of CRDS mirror microdefects and recovering CRDS measurement accuracy.

For segmented detectors, surface flatness is critical as it directly influences both energy resolution and image clarity. Additionally, the limited adjustment range of the segmented detectors necessitates precise benchmark construction. This paper proposes an architecture for detecting detector flatness based on optical fiber interconnection. By measuring the dispersion fringes for coplanar adjustment, the final adjustment residual is improved to better than 300 nm. This result validates the feasibility of the proposed technology and provides significant technical support for the development of next-generation large-aperture sky survey equipment.

The Terahertz wave possesses characteristics of high penetration, low energy, and fingerprint spectrum, etc., making it widely used in the detection field. Therefore, developing a Terahertz wave detection optical imaging system holds substantial significance and wide application prospects. Firstly, we refer to the structure of Tessar objective lens, which consists four lenses. The balance equations of aberration for the system were established through the application of the aberration theory of the paraxial optical system. Subsequently, we provide a solution function and method of the initial structure parameters of the system. Then, we combine it with optical design software to further correct the aberration of the system. Finally, we design a Terahertz wave detection optical imaging system with a large aperture. The optical system consists of four coaxial refractive lenses with a total focal length of 70 mm, an F-number of 1.4, and a full field of view angle of 8°. The value of modulation transfer function (MTF) in the range of full field of view angle is greater than 0.32 at the Nyquist frequency of 10 lp/mm, and the root mean square (RMS) radius of the diffused spot in each field of view is less than the airy disk radius. Finally, the paper analyzes and discusses the various tolerance types of the system. The results indicate that the Terahertz wave detection optical imaging system, designed in this paper, has a large aperture, a simple, compact form, a lightweight structure, excellent imaging performance and simple processing, which meets the design requirements, and it has important applications in the field of high-resolution detection and other fields within the Terahertz wave band.