The non-diffracting, self-healing, and self-bending properties of partially coherent Airy beams can suppress the influence of ocean turbulence on the transmission of signal light. The degree of optical wave coherence can be described using the complex coherence of the optical field. In this study, the cross-spectral density function of the received light field after a partially coherent Airy beam reflected by a Gaussian random rough surface in ocean turbulence is derived using the generalized Huygens-Fresnel principle. The influence of ocean turbulence, light source, and rough surface parameters, as well as other factors, on the complex coherence of the backscattered light field is analyzed. The results show that the longer the partially coherent Airy beam transmits in ocean turbulence, the lower the complex coherence of the backscattered light field, the complex coherence of the backscattered light field increases with the coherence length of the partially coherent Airy beam and decreases with the increase of the truncation factor, the speckle size at the receiving end decreases with the increase of the truncation factor, and the complex coherence of the backscattered light field decreases with the increase of the intensity of the ocean turbulence and root mean square height of the rough surface. This study establishes a theoretical basis for underwater target detection technology.

This paper reports the lateral photovoltaic effect and applications of WSe?/Si heterojunctions. High-quality WSe? films were grown on p-type and n-type Si substrates using pulsed laser deposition. The quality of the prepared WSe? films was verified through X-ray diffraction patterns, X-ray photoelectron spectroscopy, and Raman spectroscopy. The vertical I-V characteristics of the heterojunctions exhibited distinct unidirectional conductivity and high open-circuit voltage. When a point light source moved across the WSe? surface, the voltage difference between the two electrodes showed a linear relationship with the light spot position. The lateral photovoltaic relaxation times for WSe?/p-Si and WSe?/n-Si heterojunctions at 393 K were 1.1 μs and 1.92 μs, respectively, suggesting new possibilities for developing high-temperature stable sensors. Additionally, we investigated the image sensing capabilities of these heterojunctions under low-light conditions.

The QR decomposition with column pivoting (QRCP) is applied to a wavefront sensor based on the Talbot effect of two-dimensional grating, which significantly increases the number of subapertures, reduces the difficulty of sensor design, and accelerates wavefront reconstruction. After applying the QRCP method to the polynomial matrix, the number of rows of the polynomial matrix can be compressed to the same order as its columns. When reconstructing a higher-complexity and higher-order Zernike polynomial, the reconstruction speed of the solving process of Zernike coefficients increases to 224.00 times that of the traditional method, which makes it more suitable for calculations of adaptive optics. Additionally, this compression algorithm exhibits good robustness and can be applied to interferometers and Shack-Hartmann wavefront sensors. Its reduction ability creates a potential for simplifying and improving the sensor structure.

Fourier ptychographic microscopy (FPM) enables high-resolution imaging over a wide field of view; however, its reconstruction process is time-consuming. While deep-learning-based methods can substantially accelerate FPM reconstruction, they demonstrate poor generalization capability. To address this limitation, this study developed cuFPM, a CUDA-based method designed to expedite FPM reconstruction. Building on the feature-domain FPM method, a loss function incorporating edge features and its analytical gradient with respect to the optimization parameters were derived. Subsequently, parallelizable parts of the gradient computation process were identified, and parallel large-scale FPM gradient calculations were implemented using CUDA. Mini-batch stochastic gradient descent and the RMSProp optimizer were used to optimize both the complex amplitude of the reconstructed sample and the optical transfer function of the imaging system. Based on NVIDIA RTX 3090, with a reconstruction upsampling ratio of 8, cuFPM achieved average reconstruction time of 2.1 s for subregions of 512 × 512 × 145 FPM data and 43 s for those of 2048 × 2048 × 145 FPM data. The reconstructed field of view was 11 mm2, with a spatial resolution of 1024 lp/mm and a spatial bandwidth product of 165 Mpixel. cuFPM was approximately 30 times faster than CPU-based methods and six times faster than gpuArray-based methods implemented in MATLAB. On a simulation-based dataset, cuFPM achieved an average peak signal-to-noise ratio of 29.2 dB and a structural similarity index of 0.91. These results demonstrate that cuFPM substantially accelerates FPM reconstruction, providing a solution for advancing the engineering deployment of FPM and stacked imaging systems.

Limited by the instrument structure of volumetric illumination, samples outside the focal plane of wide-field fluorescence imaging can be excited and generate fluorescent signals, forming a significant defocus background that seriously interference the image data analysis. To suppress the defocus signal in a single wide-field image, we propose an image restoration algorithm based on three-dimensional (3D) point spread function (PSF) estimation and deconvolution, which efficiently removes the defocus signal. Through the reconstruction of simulated multi-layer circular rings and 3D experimental imaging of cellular actin, we verify the superiority of the proposed method in enhancing image details and improving resolution, providing an effective solution for high-quality fluorescence imaging under a wide-field microscope.

This study realizes a fiber laser based on a ring cavity, directly pumped by a 793 nm laser diode (LD) and operating in the 2 μm waveband with tunable wavelength and narrow linewidth. A tunable fiberized Fabry-Perot (F-P) filter is inserted into the ring cavity to obtain wide wavelength tuning. By using an unpumped polarization-maintaining thulium-doped fiber as a saturable absorber, a dynamic narrowband grating is generated in the cavity to achieve narrow linewidth laser output. After optimizing the lengths of gain fiber and saturable absorber fiber, the obtained output power of the laser reaches up to 70 mW and the wavelength tuning range is as high as 98 nm, and the tuning range is 1950-2048 nm. The average spectral linewidth of the narrow linewidth laser is 0.86 GHz in the wavelength tuning range. This laser can serve as a seed source for fiber amplication to obtain a high-power 2 μm laser with narrow linewidth and wide tunable wavelength.

This study proposes a array structure of one-dimensional vertical cavity surface emitting laser that utilizes the Talbot effect (Talbot VCSEL) to generate independent multi-channel chaotic signals. By extending the optical feedback rate equation, we numerically investigate the chaotic correlation of the Talbot VCSEL array under various conditions, including different feedback coefficients, optical coupling ratios, and filling factors. The results indicate that the number of coupling channels and the optical coupling ratio are influenced by the filling factor. Notably, a one-dimensional Talbot VCSEL array can produce chaotic signal output from 25 laser units within the weak light feedback range, with a feedback coefficient of less than 10 ns-1 and a filling factor of 0.7 to 1.0. Each channel exhibits low correlation, and the signal peak sidelobe level remains below 0.5.

To prepare high-quality aluminum alloy thin-walled parts and extend the service life of marine engineering equipments, the effect of laser forging composite arc additive manufacturing technology on the microstructures, porosities, and mechanical properties of thin-walled parts are studied. The results show that laser forging can effectively promote grain refinement, reduce the number and size of pores, and significantly improve the density of deposited layers and overall manufacturing quality. Microhardness and tensile experimental results show that, compared with thin-walled parts without laser forging process, the microhardness of the thin-walled parts with laser forging technology increases by 21.07%; landscape and portrait tensile strengths increase by 4.62% and 13.63%, respectively; and the elongation after breaking is also significantly improved. Therefore, laser forging can significantly improve the microstructures and mechanical properties of 5083 aluminum alloy thin-wall parts, providing an effective technical way for efficient repair and performance optimization of marine engineering equipment.

The additive manufacturing of AlSi10Mg alloy has broad applications in the production of complex structural components. With increasingly stringent service conditions for such parts, there is a growing demand for materials with enhanced fatigue performance. This study focuses on the fatigue performance of laser-selective zone-melted AlSi10Mg alloy. The fatigue life and fracture morphology of specimens under different forming directions and stress conditions are examined. In addition, the generation and propagation behavior of fatigue cracks are analyzed. The results indicate that fatigue cracks are often initiated by inclusions and tend to concentrate on or near the surface of the specimens. Increasing the maximum stress decreases the fatigue life. Further, specimens formed along the X/Y direction exhibit slightly higher fatigue life compared to those along the Z direction. Furthermore, increasing the stress concentration factor leads to a higher number of fatigue sources. Cracks often originate at the root of notches in stress concentration areas, propagating outward toward the instantaneous fracture zone.

A Cr∶ZnS main oscillation power amplifier (MOPA) laser experimental setup was designed and constructed. The oscillator adopted a four mirror folded cavity structure and achieved a continuous laser output with a power of 350 mW and a central wavelength of 2393 nm at a pump power of 3.4 W. By using a reflective grating, a tunable laser was obtained with a tuning range of 550 nm from 2075 nm to 2625 nm. The spectral full width at half maximum was 1.2 nm at the peak wavelength of 2450 nm. The oscillator was used as a seed source, the amplification characteristics of domestically produced Cr∶ZnS crystals with different doping concentrations were experimentally studied and contrastive analysis. Among them, the Cr∶ZnS crystal with the absorption coefficient of 3.3 cm-1 and the crystal dimensions of 2 mm×4 mm×8 mm exhibited the best gain output, achieving an amplification factor of 3.3. By using a two-stage amplifier, the small-signal tunable seed source was amplified. A maximum output power of 51.7 mW was achieved with a central wavelength of 2275 nm.

Traditional diode lasers typically suffer from large divergence angles and multi-mode operation at high power output, which limits their beam focusing capability and stability. This study employs a Littman-type external cavity diode laser structural model combined with classical multi-beam interference theory. A tapered diode laser is integrated with external optical components, including a transmission grating, a prism, and a flat mirror, to design and construct an external cavity diode laser capable of high beam quality and narrow linewidth laser output. When the wavelength is locked at 976 nm, the laser achieves an output power of 1.48 W, with a fast-axis beam quality factor of Mx2=1.41 and a slow-axis beam quality factor of My2=1.39. The linewidth is compressed from 10 nm in free-running operation to 0.24 nm. This laser exhibits high output power, excellent beam quality, and narrow linewidth characteristics, making it an ideal pump source for solid-state and fiber laser applications.

TA15 titanium alloy has excellent mechanical properties, but it is highly prone to passivation during electrochemical machining (ECM), forming an oxide film that hinders normal electrochemical dissolution, resulting in poor surface quality and high roughness. In this study, the oxide film on the electrolytic surface of TA15 titanium alloy is cleaned using an ultraviolet pulsed laser, and the effects of different energy densities on the microscopic morphology, elemental mass fraction, phase composition, and roughness of the cleaned electrolytic surface are examined. The experimental results reveal that the distribution of oxygen element on the electrolytic surface of the specimen is non-uniform, with the α-phase being prone to secondary oxidation at low optimal cleaning energy densities, and the β-phase, which has a higher oxygen mass fraction, requires higher energy densities for cleaning. In this study, the oxygen mass fraction of the two phases is balanced by applying the optimal energy density, resulting in lower oxygen mass fraction in both phases. The optimal cleaning parameter for the electrolytic surface oxide film is 2.39 J/cm2, at which the surface oxygen mass fraction decreases from the initial 33.17% to the minimum of 18.64%, whereas the titanium mass fraction increases from 51.65% to the maximum of 70.65%. The main component of the electrolytic surface oxide film is TiO2, and high energy densities also generate unstable suboxides Ti2O3 and TiO. As the energy density increases, the surface roughness (Ra) initially decreases and then increases, with the Ra value decreasing from the initial 4.92 μm to the minimum of 2.09 μm. The cleaned titanium alloy surface can also enhance the surface quality for subsequent ECM.

This study designs and experimentally demonstrates a strong-field nonlinear repetition rate enhancement system based on a confocal multipass cavity. By folding the optical path to focus laser pulses multiple times at the same interaction point with matter, the intracavity repetition rate is increased by more than 1 order of magnitude. The system employs an off-axis parabolic mirror-hollow roof prism composite optical configuration to construct a self-consistent transmission optical path with annular beam spot distribution. The off-axis parabolic mirror generate ring-shaped beam spots, while the rotation of the hollow roof prism adjusts the number of reflection passes during intracavity transmission, enabling multiple reflections within reflective surface. Experimental results show that when injecting fundamental light with wavelength of 1030 nm, single-pulse energy of 500 μJ, and pulse width of 800 fs, the system achieves multiple frequency doubling interactions in a barium metaborate crystal, with a single-pass second harmonic conversion efficiency range of 16%?19%. The all-reflective architecture demonstrates excellent broadband spectral compatibility and high power-handling capability, providing a novel experimental platform for studying extreme nonlinear processes such as strong-field laser-driven radiation sources.

When configuring a Doppler-eliminating optical path, the residual Doppler frequency shift in a cascaded three-level thermal atomic four-wave mixing (FWM) process is typically ignored. However, in case of a substantial wavelength mismatch between the probe and coupling light, the residual Doppler shift can considerably impact the FWM process. This study investigates the effect of the residual Doppler frequency shift on self-dressed FWM in a 85Rb hot atom D1 line system. By varying the coupling field strength, it is determined that the observed bimodal structure in the FWM spectrum corresponds to Autler-Townes (AT) splitting. These AT splits are primarily attributable to the residual Doppler frequency shift of the two-photon resonant atomic group. Further, their separation exhibits a dispersive distribution relative to the coupling light detuning, which increases with increasing coupling light intensity. The findings of this study have potential applications in the measurement of the Doppler frequency shift of optical fields and the incoherent attenuation rate of thermal atoms.

Currently, the conformal accuracy of small-tool smoothing polishing is low and does not satisfy the requirements of mid-spatial frequency (MSF) error smoothing. Hence, a small-tool polishing method for the MSF error smoothing of conical surface components based on a variable removal function is proposed. By performing theoretical modeling and finite-element simulation, the contact pressure distribution and the relative velocity model of conical surface components are established. Subsequently, based on Preston's equation, an annular removal function model is developed. By adopting the convolution principle and the constrained optimization algorithm, the dwell-time model for the small-tool polishing of conical surface components and its algorithm for conformal polishing are established. Small-tool polishing for the MSF error smoothing of conical surface components is investigated experimentally. The results show that the relative changes in the peak-to-valley value and root mean square are 13.7% and 9.3%, respectively, for a 310-mm-diameter conical mirror after smoothing. The peak value in the MSF band of the power spectral density curve decreased significantly, and the MSF error is effectively suppressed, thus confirming the correctness and feasibility of the proposed method.

With the rapid expansion of global trade, cold chain logistics becomes a critical component in ensuring the safety of food and pharmaceutical products. This study presents the development of a novel high-power deep ultraviolet light emitting diode (UVC-LED) disinfection technology aimed at addressing the survival of microorganisms and viruses, particularly the novel coronavirus (SARS-CoV-2) under prolonged low-temperature conditions. The research details the design and fabrication of a UVC-LED device based on aluminum-gallium-nitride (AlGaN) material. Additionally, ice layers with varying transparency are prepared by controlling water freezing rates, and the propagation characteristics of lightwaves through these ice layers are simulated using COMSOL software. Experimental results demonstrate the bactericidal efficacy of the light emitted by the UVC-LED device when penetrating ice and evaluate its capacity to inactivate SARS-CoV-2. The findings confirm the efficiency and reliability of high-power UVC-LED devices for disinfection in cold chain logistics. This study provides a scientific basis for the application of UVC-LED devices in cold chain disinfection and contributes to the development and optimization of future technologies.

To meet the demand for differentiated field of view of near-infrared time of flight lenses in smart home devices, this paper designs a near-infrared wide-angle lens based on a special surface using CodeV optical design software. The lens consists of four plastic lenses and one infrared bandpass filter. The four plastic lenses adopt a negative-positive-positive-positive lens structure, and the lens type is a combination of deformable non spherical and free curved surfaces. The design simulation results show that the F-number of the lens is 3.5, the maximum angle of the full field of view is 127°, the ratio of horizontal and vertical angles is 1.8:1, the total length of the system is 11.9 mm, and the modulation transfer function (MTF) is greater than 40% when the spatial frequency is 83 lp/mm, which can complete the function of near-infrared recognition and detection tasks very well.

Research on remote sensing imaging is advancing toward achieving higher ground resolution, wider fields of view, reduced weight, and improved imaging quality. Off-axis three-mirror optical systems have increasingly become a standard configuration for remote sensing cameras. However, the installation and alignment of such systems remain challenging, consequently hindering rapid prototyping and engineering implementation. Thus, this study proposes a method based on the angle between the optical axis and the installation reference surface of the aspheric component. First, non-contact measurement is employed to determine the angle between the aspheric optical axis and the installation reference surface. Subsequently, a theodolite is used to mark the zero-field-of-view reference, thereby minimizing optical axis transmission errors. Next, the secondary and tertiary mirrors are installed with high-precision coaxial alignment. Finally, the system is fine-tuned by adjusting the primary mirror. Using a low-light remote sensing camera as a case study, this method is applied to install and align an off-axis three-mirror optical system. Following installation and alignment, ground-based long-distance imaging tests demonstrates high imaging quality. In practical applications, this method enables precise pitch and yaw positioning of aspheric components, facilitates one-time high-precision coaxial alignment of the secondary and tertiary mirrors, accelerates system installation and alignment, reduces the degrees of freedom required for precision adjustments, and lowers overall installation complexity.

This study investigates a mid-infrared on-chip light source based on Ge28Sb12Se60 (GeSbSe) chalcogenide waveguides, utilizing Raman soliton self-frequency shift for wavelength tuning. The waveguides were fabricated using CMOS-compatible processes combining deep ultraviolet lithography and plasma etching. Through optimized dispersion engineering, we designed waveguides with specific structural parameters. Using a 2 μm fiber femtosecond laser with 228 fs pulse width and 27.2 MHz repetition rate as the pump source, we demonstrated continuously tunable mid-infrared Raman soliton self-frequency shift in a GeSbSe waveguide measuring 28.5 mm×1.2 μm×0.6 μm. The excitation threshold energy was as low as 4.89 pJ, with Raman soliton wavelength tunable within the 2?2.165 μm range. To extend the Raman soliton frequency shift spectrum, we propose a suspended GeSbSe strip waveguide structure designed to reduce cladding absorption and enhance optical field confinement. Numerical simulations indicate that this structure could potentially extend the Raman soliton tuning range to 3.2 μm. This research provides new insights for developing compact mid-infrared tunable laser sources, offering significant applications in molecular fingerprint identification and gas sensing.

Traditional U-slot microstrip patch antenna designs heavily rely on iterative simulations based on expert knowledge, which results in high design costs, long cycles, and low design efficiency. To address these issues, this study proposes an innovative method that integrates gated recurrent unit (GRU) models with attention mechanisms to rapidly design U-slot microstrip patch antennas, enhance their local features, and improve design accuracy. Experimental results show that this method can not only quickly and accurately predict the antenna performance spectrum in the forward direction but also inversely deduce the antenna structure design based on the desired spectrum, demonstrating high accuracy in both forward and reverse predictions. This study not only provides a new perspective for the design of U-slot microstrip patch antennas but also offers certain reference value for the design of other antennas and communication devices.

Due to the spatial constraint of arrayed vortex beams, the number of practically applicable orbital angular momentum (OAM) eigenstates remains finite. To address this limitation, this paper incorporates the generalized focusing phase and circular domain function into the vortex phase design, fabricating a vortex phase metasurface based on α-Si nanoantennas. The experimental results demonstrate the successful generation of concentric generalized perfect vortex beams (G-PVBs). This novel design transcends the constraint of conventional vortex beam symmetry, featuring distinct vortex shapes and spiral lobes in the beam pattern, with spiral interference patterns arranged concentrically without overlap. The approach effectively decouples the shape, topological charge, number of vortex beams, and polarization characteristics. Each vortex beam maintains stable topological charge and shape information, successfully preventing intermodal crosstalk. Through this efficient concentric configuration, this research achieves spatial multiplexing, polarization multiplexing, and OAM mode multiplexing of perfect vortex beams. This advancement expands the communication channels and information dimensions in vortex beam communications, offering significant potential for high-capacity encrypted vortex beam communication systems.

Both cardioid and hexadecagonal binary amplitude diaphragms (BADs) can effectively suppress axial intensity oscillations of Bessel beams, enhancing their potential applications in practical optical systems. However, various experimental deviations during fabrication, testing, and application processes can affect the suppression performance of axial intensity oscillations when Bessel beams transmit through the above two BADs. These deviations include random amplitude variations in incident light, incident beam shape deviations, incident beam center alignment errors, and pixel precision deviations in microlithography processes. Based on scalar diffraction theory and the complete Rayleigh?Sommerfeld method, we conducted numerical simulations and analysis to evaluate how these experimental deviations affect the oscillation suppression performance of the cardioid and hexadecagonal BADs. The numerical results demonstrate that both BADs maintain robust suppression capabilities against the four types of experimental deviations, even under significant deviation conditions. These findings provide valuable guidance for practical applications requiring stable Bessel beam propagation.

Contact is a universal thermodynamic quantity crucial for studying short-range pairing correlations in strongly interacting Fermi gases. It serves as a vital bridge connecting the system's microscopic short-range physics with its macroscopic thermodynamic properties. In this study, we developed a novel two-photon Raman coupling technique for strongly interacting ultracold Fermi gases. This method can switch the interaction to a non-interacting state on timescales much faster than the system's Fermi time, enabling instantaneous measurement of thermodynamic parameters. Our measurements reveal that in the high-momentum region, the atomic gas momentum distribution exhibits a 1/k4 scaling behavior characteristic of Contact, allowing precise determination of the Contact coefficient. Comparison of our experimental results with traditional RF spectroscopy methods and theoretical calculations demonstrates that the two-photon Raman technique achieves accurate Contact measurements comparable to RF methods. Additionally, it offers advantages in transient measurements and immunity to final-state scattering effects. These findings provide crucial experimental evidence for understanding the microscopic mechanisms of strongly correlated Fermi gases.

Coal moisture content is an important index for evaluating coal quality and environmental governance results. Excessive coal moisture content can reduce coal quality, and insufficient coal moisture content can produce a large amount of coal dust and pollute the environment. In this study, non-Hermitian singularities in a second-order parity-time (PT)-symmetric system are used to study and analyze the moisture content of coal, and small changes in the moisture content are observed using the difference between the dielectric constants of water and coal. Compared with the traditional passive wireless sensor, the second-order PT-symmetric passive wireless sensing system improves detection sensitivity, generating a smaller error of less than 0.05% compared with the drying method. Compared with other detection technologies, this system has the advantages of online measurement of coal moisture content, good real-time performance, and high safety, which has certain significance for improving coal quality and the safety of the coal industry.

Optical manipulation technology has rapidly developed into a significant research area in recent years, which utilizes light-matter interactions to capture and control objects. Due to its non-contact, non-destructive, and high-precision manipulation, this technology exhibits substantial potential in fields such as life science, quantum information, and precision measurement. Notably, optical pulling and lateral forces, as critical mechanical effects that transcend traditional limitations of optical manipulation, have garnered considerable research in light manipulation. This article reviews the progress in optical pulling and lateral forces by analyzing their generation mechanisms, implementation approaches, and application potential in areas like optical sorting, micro-nano robotics driven, and life science. Additionally, it systematically reviews and discusses the development histories of optical lateral and pulling forces, and explores future prospects and challenges within this dynamic field.

Femtosecond laser fabrication technology enables high-precision three-dimensional (3D) direct writing, allowing the on-demand fabrication of 3D coupled waveguide systems for constructing 3D photonic integrated chips. This review summarizes recent advances in 3D photonic integrated chips based on femtosecond laser direct writing (FLDW) optical waveguides in the fields of photonic quantum computation and non-classical physics. For photonic quantum computation, this review highlights the logic gates for universal photonic quantum computation, quantum-walk-based specialized photonic quantum computation chips, and topologically protected photonic quantum computation chips. For non-classical physics, the review focuses on applications of 3D photonic integrated chips in nonreciprocal photonics, non-Hermitian physics, and non-Abelian physics, exhibiting the exceptional capabilities of 3D photonic integrated chips. Finally, key challenges faced by the practical application of FLDW 3D photonic integrated chips are analyzed and potential solutions for limited integration density, difficult gain implementation, poor tunability, and weak nonlinear response are proposed.

X-ray detection and imaging technology, as a crucial tool for modern material analysis, has been widely implemented in medical diagnosis, industrial non-destructive testing, and aerospace precision analysis. This review focuses on the core components of X-ray detection systems—photoelectric conversion materials and device architectures, systematically summarizing recent research progress of metal halide semiconductors in this field. These materials demonstrate exceptional X-ray attenuation capabilities and long carrier diffusion lengths due to their high atomic numbers. Combined with solution processability that enables low-cost manufacturing, they show tremendous potential for next-generation radiation detection. We first introduce the interaction mechanisms between metal halides and X-ray. Then, we enumerate key parameters affecting detection and imaging performance, thoroughly discussing strategies to optimize detection performance through material design and device engineering, covering both direct and indirect X-ray detection approaches. Finally, we summarize the main challenges facing current X-ray detectors and their potential solutions, followed by perspectives on future development.

Ultrafast long-wave infrared (LWIR) lasers show promising applications in strong-field laser physics, including particle accelerators and high-harmonic generation. This review first summarizes recent developments in femtosecond LWIR laser technology. CO2 lasers have achieved terawatt-level peak powers. However, discharge excitation under high-pressure conditions faces challenges in achieving high repetition rates. While nonlinear optical frequency conversion techniques enable high-repetition-rate and few-cycle laser outputs, they encounter bottlenecks in achieving high peak powers. High-pressure CO2 amplifiers present a potential solution for generating terawatt-level, few-cycle LWIR laser outputs. The review then examines the current state of high-pressure CO2 laser amplifier research, focusing on developments and trends in optically pumped high-pressure CO2 laser amplifiers. Finally, it analyzes and discusses technical approaches for high-pressure CO2 amplification of femtosecond LWIR lasers.

Efficient and accurate perception of environmental color information is pivotal in imaging technologies. However, the field currently faces technical bottlenecks such as color inaccuracy and optical energy loss. Micro-nano photonic technologies, which manipulate light fields via micro-nano structures, play a crucial role in enhancing image acquisition, improving color reproduction, increasing optical energy utilization, and promoting system miniaturization. This article systematically reviews the design principles and research progress of high-efficiency color routers based on nanophotonic structures. By comparing the physical mechanisms of nanophotonic color routers with those of traditional spectral filters, we elucidate the unique advantages and vast application potential of nanophotonic approaches. We focus on analyzing the differences in color-routing performance among metallic materials, low-refractive-index materials, high-refractive-index materials, and their two-/three-dimensional nanostructures, along with their respective merits and limitations. Furthermore, by examining recent trends, we prospect the future development of nanophotonic color routers in terms of resolution, color fidelity, and on-chip integration, providing a roadmap for their applications in advanced imaging systems.

The output power of a single-beam fiber laser has a theoretical limit, and high-power fiber laser beam combining technology is the key to achieving ultra-high power while maintaining high beam quality. This paper analyzes on the limiting factors for power increasing in high-power fiber lasers, and reviews principles, technical characteristics, and current technological statuses of different beam combining schemes. Among these, chromatic beam combining using dichroic mirrors demonstrates significant engineering advantages for power increasing and beam quality preservation in broadband laser systems. The paper reviews the developmental progresses in pulsed and continuous wave fiber laser chromatic beam combining technologies in both domestically and internationally, introduces key technologies and researches in this field. Finally, future prospects for chromatic beam combining technology are discussed.

The proposal and development of optical topological edge states have opened up a new direction for solving the problem that traditional photonic devices are vulnerable to impurity interference, which can significantly enhance the robustness of electromagnetic wave propagation and is of great significance for the design of new photonic devices. As a metamaterial, plasma can effectively control the propagation of electromagnetic waves. Its hyperbolic dispersion characteristics, negative permittivity and time-varying characteristics create advantages for exploring novel plasma topological phases, and are expected to promote the development of black barrier electromagnetic communication technology, tunable microwave devices and photonic time crystals. Based on the development process of plasma photonic crystals, the generation methods of plasma arrays, such as dielectric barrier discharge, plasma jet, glow discharge, etc., are briefly reviewed, and the characteristics such as nonlinear Kerr effect, flat-band localized mode, non-reciprocal propagation in magnetized plasma are discussed. The development process and research status of topological phases in plasma are further reviewed in detail, and the schemes for realizing topological edge states by means of solid-state semiconductor materials, gas discharge plasma, dielectric-plasma composite structures are introduced. Finally, the development status, advantages and challenges of the topological characteristics of discharge plasma are summarized and prospected.

With the growing demand for the miniaturization and integration of coherent light sources, the research of micro and nano lasers has become a hot spot in the field of basic physics and optoelectronic devices. In recent years, the rapid development of new semiconductor materials and nano processing technology has significantly improved the performance of micro/nano lasers. In this paper, the development status of micro/nano semiconductor lasers is systematically reviewed, including the resonance mechanism based on different types of optical microcavities, the application of diversified gain materials (especially perovskite semiconductor), as well as new mechanisms such as exciton polariton laser and superradiance. Finally, the challenges and future development of micro/nano semiconductor coherent light sources are prospected.

Deep learning-based imaging through scattering media has emerged as a crucial research direction in computational optical imaging, garnering significant attention in recent years. While supervised learning approaches have made notable progress in this field, they still face numerous challenges in practical applications and key technologies. For instance, supervised learning heavily relies on precisely paired training data, which is extremely difficult and impractical to obtain in complex scattering environments. Moreover, supervised imaging methods often demonstrate poor generalization performance when confronting scenarios outside their training scope, due to the limited representational capacity of data samples. To address these challenges, unsupervised training strategies for imaging through scattering media have gradually become a research focus, yielding remarkable results. This paper classifies various network frameworks in unsupervised learning-based scattering media imaging from a neural network perspective. We categorize existing unsupervised learning-driven scattering imaging techniques into four types: autoencoder-based, generative adversarial network-based, diffusion model-based, and convolutional neural network-based unsupervised scattering imaging technologies. For each method, we provide detailed analysis of their performance advantages and limitations. Finally, we present future development prospects for neural network-based unsupervised imaging through scattering media. This review aims to help researchers understand the principles and latest developments in various unsupervised scattering media imaging techniques, clarify the characteristics and applicable scenarios of different technologies, thereby advancing the engineering application process of scattering media imaging technology.

Single-pixel imaging is an integral imaging method that combines optical modulation and computational reconstruction. This paper reviews the progress of single-pixel imaging, light field modulation, compressed sensing, and deep learning, as well as their applications in wavefront reconstruction, scattering imaging, image encryption, and quantum imaging. It introduces orthogonal modulation and compressed sensing, exploring the progress of deep learning and physical drive in improving imaging speed, fidelity, and robustness. At the same time, it points out the challenges of single-pixel imaging in terms of real-time performance, noise suppression, and environmental adaptability.

In traditional condensed matter systems, the strong electron correlation effect is often weakened by shielding mechanism and lattice constraints. Graphene forms a unique non Fermi liquid state, Dirac fluid, near the electric neutral point by virtue of its linear dispersion relationship, the unshielded nature of long-range Coulomb interaction, and the relativistic dynamics of massless carriers. It has become an ideal platform for studying quantum critical transport and collective fluid behavior. In recent years, with the continuous development of high-quality material preparation technology, many theoretical predictions of Dirac fluid have been verified. Based on the band structure of graphene and the theoretical framework of Dirac electron hydrodynamics, this paper systematically reviews the key experimental progress in this field, including the universal scale of quantum critical conductivity, the significant violation of Wiedemann Franz law, the non local transport behavior of viscous flow, and the imaging technology of real space electron flow field.

As a passive means of laser protection, optical limiting technology based on nonlinear optics has received extensive attention from researchers in recent years, and optical limiting materials are its crucial components. The development of high-performance optical limiting materials is of vital significance for the construction of protective systems to cope with the increasingly severe threat of high-intensity lasers. This review introduces the basic principle of optical limiting and summarizes the research progress on optical limiting materials (including organic small molecules, metal complexes, carbon-based materials, semiconductor nanomaterials, etc.) based on different nonlinear optical mechanisms (such as reverse saturable absorption, nonlinear scattering, and nonlinear refraction). Finally, future research directions for optical limiting materials are proposed.

The Moon is the only natural satellite of Earth. Lunar exploration and development have regained international attention in the 21st century, becoming a key area of space exploration. Recently, China has proposed the International Lunar Research Station (ILRS) program, aiming to establish long-term operational scientific research facilities to achieve lunar scientific research and resource utilization objectives. This paper summarizes the potential needs and representative applications of multiple optical technologies in various aspects of the ILRS program (including scientific research, system construction, energy management, and environmental control). The technical challenges of optical technologies in lunar exploration are briefly discussed. This paper could provide useful insights for researchers in related fields.

Nonlinear optical effects, as a crucial form of light-matter interaction, constitute one of the physical foundations for modern photonic technologies, including high-speed all-optical communication, information processing, and quantum computing. The efficient control of these effects directly determines improvements in optical field energy conversion efficiency. Nonlinear chirality, an emerging interdisciplinary direction in nonlinear optics, combines symmetry breaking in chiral structures with nonlinear optical field manipulation, offering new approaches for single-molecule chiral recognition, ultra-pure circularly polarized light emission, and ultra-integrated photonic device development. In recent years, advances in micro-nano photonics and related technologies have significantly facilitated the customization of subwavelength-scale nonlinear chiral responses. This review first traces the development and control mechanisms of nonlinear optical effects, emphasizing the role of various electromagnetic resonance mechanisms in modulating nonlinear chiral effects. Subsequently, it examines research progress and applications in enhancing and controlling nonlinear chiral effects through micro-nano structures, focusing on specific phenomena including second-harmonic generation, third-harmonic generation, sum-frequency generation, and difference-frequency generation. Finally, it presents future perspectives, highlighting potential intersections with multiple frontier fields such as multifunctional integrated photonic devices, artificial intelligence, and quantum optics, providing valuable references for the continued development of nonlinear chiral optics.

An inversion method for optical thin-film parameters based on reflection spectra is proposed, which does not require recording the phase and extremum of the reflection spectra. The complex refractive index and film thickness of optical thin films can be inverted using the reflectance amplitude, thus overcoming the disadvantage of existing techniques for measuring high-absorption thin films. This study analyzes reflection-spectrum data at different incident angles and uses the functional relationship among film reflectance, refractive index, and thickness to obtain the intersection points of reflection spectra in the refractive index-extinction coefficient planes at different incident angles. By integrating a global optimization algorithm, the refractive index and extinction coefficient values at various thin-film thicknesses for different wavelength nodes are solved. We identify the probability density distribution of the thin-film thickness corresponding to each wavelength node and utilize the results corresponding to the highest probability density of the most likely film thickness as the optimized thickness. Subsequently, a secondary inversion is performed to ascertain the optical parameters of the thin film. The proposed approach is applicable even when the optical characteristics of the material are unknown, as it does not necessitate fitting the material's refractive index. During the numerical-verification phase, the accuracy of the proposed method in inverting the optical parameters of high-absorption thin films is demonstrated via two computational examples. The proposed method provides a new practical tool for the development of optical thin-film technology, which is expected to promote its further application in multiple fields.

Superconducting thin-film infrared detectors exhibit characteristics such as high sensitivity, wide response band, high response speed, low noise, and low power consumption, making them a remarkable application of superconducting materials. Artificial nanoporous structured high-temperature superconducting thin films not only feature critical temperatures above the liquid nitrogen temperature range but also possess superconducting-insulation phase transition characteristics with potential applications in infrared detection. This study focuses on two types of copper-based high-temperature superconducting materials, namely thallium barium calcium copper oxide (Tl-2212) and yttrium barium copper oxide (YBCO), to investigate the infrared light response characteristics of artificial nanoporous structured high-temperature superconducting thin films. First, a time-domain finite-difference simulation model of high-temperature superconducting nanoporous thin films is established. By comparing the light response characteristics of uniform and porous thin films, an equivalent medium model-based approach for light response modeling is determined. Next, the equivalent error of three equivalent models of the light absorption rate under different thin-film thicknesses is evaluated. The results show that the Maxwell-Garnett model provides high accuracy in approximating the optical properties of artificial nanoporous high-temperature superconducting thin films. Finally, using the particle swarm optimization algorithm, the light absorption rate of back-illuminated artificial nanoporous high-temperature superconducting thin films loaded with optical cavities is optimized for a single wavelength of 1550 nm in the near-infrared range and the broadband range of 3?5 μm in the mid-infrared. The strong agreement with the full-wave simulation results confirms that the Maxwell-Garnett equivalent model ensures high design accuracy while simplifying the design process. Additionally, for a 30 nm thick film, the light absorption rate of the nanoporous structured Tl-2212 thin film at 1550 nm reaches 97.13%, while the nanoporous structured YBCO thin film achieves at least 80% light absorption rate in the range of 3000?3797 nm. These results provide a valuable reference for the design of superconducting infrared detectors.

Hydrogen transfer processes are ubiquitous in various physical, chemical, and biological reactions, involving chemical bond breaking, reorganization, and changes in molecular configuration. Real-time observation of hydrogen transfer processes is therefore crucial for understanding molecular dynamics and precisely controlling physicochemical reactions. In recent years, hydrogen transfer in molecular dimers has attracted considerable attention. The measurement of hydrogen transfer characteristic times provides key insights into reaction pathways in clusters and reveals intermolecular interactions. Using the atom-centered density matrix propagation method combined with extended Lagrangian molecular dynamics simulations, we investigated the ultrafast dynamics of hydrogen transfer in the dissociation process of (NH3-H2)+. The average hydrogen transfer time was determined to be 224 fs. By tracking the evolution trajectories during hydrogen transfer, we discovered two distinct channels with different transfer times. The results indicate that these channels are closely related to the kinetic energy conversion between different vibrational degrees of freedom during hydrogen transfer and significantly correlate with the initial intermolecular distance. This discovery provides valuable reference for studying hydrogen transfer dynamics in more complex molecular aggregate systems.