Real time generation has been achieved for 8K full color rainbow hologram with normal PC. We extended previous 4K rainbow hologram calculation to 8K resolution, 7,680 x 4,320 pixel. The hologram is calculated with a line source approximation that can accelerate computation speed faster than the previous slit model based on image hologram calculation. Experimental results show that holograms are generated and displayed about 18 frames per second with 140,000 points. Additionally, the current line source model calculates 8K holograms 1.6 to 2.3 times faster than the previous slit mode.

Polygon-based computer-generated holography algorithms can achieve high realism at low computational cost. Many recent contributions improve the hologram generation efficiency and solve many issues of 3D realistic rendering. This manuscript provides a comprehensive evaluation of their performance and potential through a detailed classification and comparison. Although the numerical-based algorithms using spectral interpolation offer greater flexibility in achieving realistic 3D displays, further phase-optimization algorithms are needed to render 3D reconstructions with higher definition, reduced noise, and faster updates.

Over 1kHz reconfiguration of computer-generated holograms (CGHs) was implemented with a ferroelectric liquidcrystal- on-silicon spatial light modulator (FLCoS-SLM). The high-framerate reconstructions were performed on the 6.3 kHz pulse-to-pulse spatial light modulation. The reconfiguration speed will drastically change the applicability to science and industrial fields and open a door for new CGH applications. In this research, it was applied to parallel femtosecond laser material processing.

Structured light beams, with unique spatial properties, are applied to rapid three-dimensional (3D) imaging in laser scanning microscopy. Our proposed method utilizes a needle-shaped excitation spot and wavefront modulation of fluorescence signals to retrieve depth information from a single raster scan. The combined use of these techniques eliminates the need for multiple focal plane acquisitions, significantly improving 3D image acquisition speed. The effectiveness of this technique was demonstrated by capturing the 3D Brownian motion of nanoparticles. This approach holds promise for rapid 3D volumetric imaging in various fluorescence microscopy applications.

Holographic three-dimensional (3D) display is one of the current research hotspots in the field of true 3D display. It records and reconstructs the wavefront information of a 3D scene, and is able to provide all the depth cues required by the human eye. The point-source method is the most accurate way to calculate computer-generated holograms (CGHs) for holographic 3D display. However, it usually needs a lot of computation, especially when calculating full-parallax CGHs, which requires rendering the 3D scene from each perspective and superposition of complex amplitudes from the point sources for each pixel on the hologram plane. Serial calculation using central processing units (CPUs) is timeconsuming and difficult to meet actual demands. In this paper, OpenGL shaders are utilized to realize fast calculation of CGHs. Taking advantage of the highly parallel architecture of the graphics processing unit (GPU), OpenGL shaders are used to process the data of 3D objects, compute amplitudes of the sampling points, and implement superposition and phase extraction in parallel. Finally, Phase-only holograms are obtained by this method. Images of the scene are reconstructed from the generated holograms to verify the correctness of the proposed method. Comparing the time taken by MATLAB and OpenGL to generate holograms of three different 3D models under the same conditions, the calculation method based on OpenGL shaders proposed in this paper can significantly shorten the computation time. The computation speed is increased by up to 600 times. It is expected to achieve real-time calculation of full-parallax CGHs and promote practical applications of holographic 3D display.

This work is devoted to studying the efficiency of excitation and support of waveguide modes for a non-Hermitian optical system consisting of two thin optically coupled subwavelength periodic structures. Excitation modes of various modes were studied depending on the angle of incidence of the exciting field for the visible and near-IR ranges for TE and TM polarizations. The possibilities of excitation of single-mode regimes with high field localization in thin subwavelength structures, as well as regime of hybridization modes, have been studied. The excitation modes of the unidirectional waveguide mode, when linearly polarized light (TM) is incident on an optically coupled system of two subwavelength periodic structures, have been separately studied. We analyzed the Q-factors for various permittivity modulation profiles, as well as the features of the eigenstates of the system under consideration, and studied the behavior of the system near exceptional points, which can be effectively used to control the switching of waveguide modes. Research was carried out, in particular, for AlGaAs/GaAs lattices, for which a decrease in the thickness of the active region leads to a decrease in the optical confinement factor and a decrease in the lasing threshold.

In recent years, two-dimensional materials with outstanding chemical stability and bioaffinity have gained significant traction in the field of biosensing. Here, we present a surface plasmon resonance (SPR) sensor based on a two-dimensional MoSe₂@Zr₂CO₂ heterostructure, utilizing the Kretschmann configuration. Through comprehensive simulations, we optimized the structural parameters to enhance sensor performance. Initially, we explored the effect of varying MoSe₂@Zr₂CO₂ layer numbers on SPR wave propagation and identified 16 layers as the optimal configuration for maximizing plasmonic performance. Subsequently, we analyzed the influence of dielectric thickness and refractive index on sensor sensitivity, yielding optimal structural parameters. Finally, we examined the impact of different prism refractive indices on sensor performance, finding that lower refractive index prisms effectively boost sensitivity. Thanks to enhanced light absorption and surface plasmon resonance effects, this sensor exhibits substantial improvements in detecting biomolecules. Compared to conventional SPR sensors employing a 50 nm gold film, the MoSe₂@Zr₂CO₂-based sensor demonstrates an 8-fold increase in the figure of merit (FOM), along with higher sensitivity (92.48°/RIU) and an enhanced FOM (319.63 RIU⁻¹) in the visible spectrum.

Asymmetric metasurfaces supporting quasi-bound states in the continuum (-BIC) are especially important for photonic devices because they provide high-quality factor (Q-factor) resonances. However, asymmetric metasurface structures are susceptible to the polarization state of the incident light, which limits their potential applications. In this paper, we propose a new design scheme for polarization-independent quasi-BICs without resorting to rotationally symmetric and tetramer structures. Consistent quasi-BIC resonances are observed in the metasurface consisting of asymmetric double nanorods under incident light with different polarizations. Studies of the far-field multipole decomposition and near-field distribution show that different multipoles exhibit different dependencies on the direction of polarization and that transitions between magnetic and electric quadrupoles lead to polarizationindependent quasi-BIC resonances. This work provides a new idea for designing polarization-independent high Qfactor resonators and promotes a broader range of potential applications.

Polarization information analysis is of great significance in military target reconnaissance and preventing weather interference such as rain and fog, and has advantages in highlighting artificial targets and identifying materials. The polarization bidirectional reflection distribution function (pBRDF) model has attracted the attention of scholars due to its ability to well describe the reflection and scattering of polarized light on object surfaces, and has important applications in the field of polarization detection. However, most of the existing pBRDF models have not accounted for the polarization characteristics differences caused by object color differences, which has significant limitations in practical applications. Therefore, in this article, we validated the classic pBRDF models through experiments and pointed out their existing problems. Then, through theoretical and experimental analysis, we proved that considering only specular reflection in the PBRDF model is insufficient, and analyzed the influence of different colors on the the Degree of Liner Polarization (DoLP) of objects. In addition, we also analyzed the influence of target surface roughness on object surface polarization, proving that considering roughness in the pBRDF model is correct. Finally, we analyzed the possible improvement directions for the pBRDF model in the future. Our work has made valuable explorations into the physical interpretability of polarization characteristics and the practical application of polarization detection.

The optical configuration of the in-line digital holography is compact and simple, but the presence of twin images limits its application. In this work, we introduce an iterative projection optimization algorithm via combined constraints framework (CCF). Specifically, Positive absorption constraints, total variation minimization, and denoising regularization are introduced in the optimization framework to ensure the authenticity of the reconstructed target wave complex amplitude field and the signal-to-noise ratio of the reconstructed image. The feasibility of our method has been verified through the optical experiments. Compared with existing methods, this method has higher imaging fidelity.

In the process scenario of combining contact lithography and laser interference lithography, the gap between the mask and the substrate may cause a series of problems, such as reducing the contrast of the pattern, misalignment of the two interference beams, and unexpected macroscopic patterns. This article introduces a method of adding refractive index matching liquid to suppress interference caused by gaps. Matching liquids can buffer the refractive index changes at the interface of the medium. As a result, the reflectivity of the medium interface decreases, thereby suppressing harmful macroscopic patterns. In addition, matching liquids can reduce the refractive angle of interference beams, thereby reducing their misalignment and increasing the area ratio of effective patterns. This article identified suitable matching liquid materials and conducted numerical simulations and analysis to demonstrate the effect of adding matching liquid on improving pattern contrast. For the production of gratings ranging from 550nm to 1500nm, the stripe contrast is below 0.05. In summary, the most suitable refractive index matching liquid has been explored and tested under the given refractive index of the mask and substrate. Experiments have shown that adding matching liquids can provide significant advantages.

We propose a spatiotemporal optical differentiator of the first order based on a three-layer metal-dielectric-metal (MDM) structure operating in reflection. For describing the transformation of the incident spatiotemporal optical signal, we apply the transfer function formalism of the theory of linear systems. We demonstrate that the differentiator based on the proposed MDM structure enables generating a reflected optical pulse possessing an optical vortex in the spatiotemporal domain (referred to as the spatiotemporal optical vortex, STOV). The MDM differentiator can also be used for high-quality edge detection of the incident spatiotemporal optical signal. Moreover, we investigate a “double” MDM structure consisting of two single (three-layer) MDM structures separated by a dielectric layer, which implements the operation of spatiotemporal differentiation of the second order. By considering the generation of a reflected optical pulse with several phase singularities and studying the edgedetection operation, we show that the operation of second-order spatiotemporal differentiation is implemented with high accuracy. We also investigate the possibility of obtaining an STOV in asymmetric and symmetric dielectric slab waveguides and demonstrate that an STOV can be generated upon reflection of a spatiotemporal optical pulse propagating in the waveguide from an integrated metal-dielectric structure consisting of a few metal strips “buried” in the waveguide core layer. The obtained theoretical results are in good agreement with the results of rigorous numerical simulations of the spatiotemporal differentiation and STOV generation using metal-dielectric structures in both free-space and integrated geometries. We believe that the obtained results may find application in the creation of analog optical computing and optical information processing systems.

The Dammann Grating (DG), a binary phase grating, efficiently divides incident light into equal-intensity sub-beams, making it ideal for beam splitting applications. In this research, an array-pumped, microchip Nd:YVO₄ laser was explored by incorporating a DG into the collimation part of the pump optical path, to obtain single-longitudinal-mode (SLM) and multi-beam output at 1064 nm. As a result, 2×2 arrayed output of the laser was obtained with a total output power of 558.0 mW at 1.86-W pump power, exhibiting a slope efficiency of 36.3%, offering distinct advantages in SLM operation due to its thermal management capabilities in homogenizing thermal gradients and thus resulting in highpower operation with high beam quality. Except for the 2×2 array pumping, high-power SLM operation also can be expected by applying higher-order array pumping.

Optical array is proposed and widely used in processing, communication, microscopy, storage and other fields. However, the current methods to generate optical array are only effective in specific scenarios. In this work, we present an efficient and general method, which separates iterative calculation and parameter selection by introducing a special mapping space, allowing the generation of optical arrays with arbitrary dimensions, optional parameters and any energy ratios. This method is compared with traditional methods from both simulation and experiment, and is superior in diffraction efficiency, focus amount, and calculation speed. Additionally, a 5-dimentional optical array with specially-designed parameters is produced to show the versatility for different parameters. It shows advantages in beam shaping and parallelization, and will be instrumental for applications in information storage, industrial processing, and three-dimensional imaging.

Holographic displays are widely regarded as the pinnacle of three-dimensional (3D) visualization technology. In these displays, real objects must be either photographed or converted into 3D models, which are then processed through neural networks or sophisticated algorithms to generate 3D holograms. To address this challenge, we propose an end-to-end 3D hologram generation strategy that integrates the Transport of Intensity Equation (TIE) phase retrieval technique with the Double Phase-Amplitude Coding (DPAC) method. Under coherent light illumination, phase-only holograms containing depth information can be directly generated by capturing out-of-focus amplitude maps of object light waves propagating to the holographic plane via a camera. The TIE module processes the two out-of-focus amplitude maps to resolve the phase and subsequently generates a phase-only hologram through DPAC. We further conduct simulations to validate the phase retrieval capability of the TIE on complex holograms and demonstrate the feasibility of our proposed strategy.

Holographic data storage technology is a cost-effective technology for long-term archival data storage, and the preparation of suitable holographic recording materials is still a challenge. Among them, phenanthraquinone doped poly(methyl methacrylate) (PQ/PMMA) stands out among photopolymers due to its low cost and controllable thickness. Due to the low diffraction efficiency and photosensitivity of the photoinduced polymer PQ/PMMA material itself, the storage capacity and recording speed of the holographic memory are severely limited. Modification of PQ/PMMA by introducing inorganic nanoparticles, organometallic components, or copolymers has been reported in the literature, but these do not significantly improve its sensitivity. Most of these strategies involve upward modification of the PMMA matrix. Here, we propose a new strategy of introducing organic solvents (such as N-Methylpyrrolidone (NMP), N,NDimethylformamide (DMF)), and modifying the matrix by the principle of subtraction to improve the optical properties by controlling the final residual content of the monomers. The resulting photopolymer exhibits excellent photosensitivity and high diffraction efficiency. This strategy provides new ideas for the modification of photopolymers.

With the advent of the big data era, massive data needs to be stored. Holographic storage has become a strong contender for the new generation of storage technology due to its advantages of multi-dimensional modulation and three-dimensional storage. Phenanthrenequinone-doped poly (methyl methacrylate) (PQ/PMMA) is a popular research for holographic storage materials due to the easy availability of raw materials, low cost and simple preparation process. At present, PQ/PMMA materials are basically made manually, but there are differences in the materials prepared by different people. Therefore, we designed an automated material preparation platform, which has more stable characteristics than manual preparation. On this basis, we investigated the effect of ambient temperature and humidity on the properties of holographic materials, and provided new suggestions and guidance for the research of holographic materials.

Since their conception as Diffractive Deep Neural Networks (D2NNs) by Lin in 2018, the field of optical information processing with sub-wavelength patterned thin scatterers has raised significant attention, as it not only allows for leveraging the inherent advantages of optical signals, such as parallelism and high speed, but also allows for convenient processing of optical information in its native domain. The nanoprinting of such diffractive networks with two-photon polymerization methods is of interest, as it allows for fabrication of optical inference systems with record-high neurons densities, targeted for the VIS/NIR wavelength regime and fabricated directly on commercial CMOS imaging sensors. Current methods for in-silicon training of these Diffractive Neural Networks employ numerical models of ‘masked’ detectors, where only certain areas of the networks output plane are compared for performance evaluation, while the remainder of the detector area is being ignored. While such training methods have the advantage of straightforward numerical implementation, for fabricated devices where typically the whole output plane in captured for data acquisition, this can lead to significantly reduced performance due to strong background signals in the areas that were ‘masked off’ during training and hence susceptibility to errors in aligning the distinct detector areas for readout. In this contribution we critically discuss methods for training of diffractive neural networks which consider the whole output plane of the network in order to achieve low background noise and hence high detector-to-background contrast for 3D nanoprinted diffractive neural networks with increased experimental robustness due to reduced susceptibility for errors in alignment of detector areas.

We propose a redefinable neural network (RediNet), realizing general modulation on diverse structured light arrays through a single approach. Exploiting the information sparsity of the array distribution, a redefinable dimension designation is used in RediNet, removing the burden of processing pixel-wise distributions. The prowess of originally generating arbitraryresolution holographs with fixed network is firstly demonstrated. The versatility is showcased in the generation of 2D/3D foci arrays, Bessel and Airy beams arrays, (perfect) vortex beam arrays, multi-channel compound vortex arrays and even snowflake-intensity arrays with arbitrarily-built phase functions. Considering the fine resolution, high speed, and unprecedented universality, RediNet can serve extensive applications such as next-generation optical communication, parallel laser direct writing, optical traps, and so on.

This paper introduces a deep learning-based low-light lensless image reconstruction enhancement algorithm that can effectively reconstruct low-light lensless images and achieve significant enhancement effects under low-light conditions. The algorithm comprises two stages: (1) A preliminary imaging stage, where the forward imaging model is utilized as a prior knowledge to obtain the initial reconstruction results; (2) A perceptual enhancement network built upon the conditional diffusion model for detailed enhancement, resulting in realistic images with normal lighting and reduced noise. Experimental results on simulated datasets demonstrate that this algorithm exhibits superior reconstruction performance with Learned Perceptual Image Patch Similarity (LPIPS) and Structural Similarity Index Measure (SSIM) up to 0.0887 and 0.7454, respectively, and successfully realizes the reconstruction and enhancement of lensless low-light images.

In this paper, we evaluate the noise sensitivity of mask based lensless imaging by analysing how much information is lost due to camera noise in low-light conditions. A noise model based on a lensless imaging system under lowlight conditions is presented for noise analysis in lensless imaging. The structure utilises the noise-free point spread function (PSF) of a diffuser-based lensless system to generate a noisy PSF from a camera in a real-world low-light environment. We then use a statistical approach to observe how the amount of mutual information between the noiseless and the noisy PSF’s is affected with the enhancement of camera noise. We performed the same simulation for comparison with lens-based imaging. We demonstrate that the proposed model and the mask based lensless imaging system exhibits better robustness than the lens-based imaging system in low-light environments.

In holographic near-eye displays, enhancing the user experience by expanding the eyebox without compromising the field of view (FOV) is crucial. Current technologies face limitations due to optical etendue, making it difficult to simultaneously achieve a large eyebox and a wide FOV. This paper presents a novel portable augmented reality holographic near-eye display system that expands the exit pupil without reducing the FOV, using exit pupil scanning technology. The system replaces conventional eyepieces and beam splitters with holographic optical elements, employs point light source illumination instead of collimated illumination, and utilizes an off-axis angular spectrum diffraction propagation model between parallel planes tailored to human visual characteristics. This approach effectively mitigates the trade-off between FOV and eyebox. Compared to traditional systems, the proposed design resolves this trade-off in simulations and reduces the form factor, offering a promising new approach for practical holographic near-eye display applications.

Auto-focusing plays a crucial role in lens-free holographic microscopy. In this research, we propose a new axialdifference- based Robert method aimed at improving the accuracy of distance estimation under wide-spectral illumination. By establishing connections between intensity derivation, spectral distribution changes, and object distribution, we develop a robust method. The procedure involves image acquisition, preprocessing, axial difference computation, and sharpness-based distance determination. Both simulations and experiments verify the method’s ability to enhance auto-focusing accuracy in wide-spectral illumination scenarios. To demonstrate its broad applicability, experiments are carried out using ultra-wide-spectral illumination on various samples, including a resolution target and a Tilia stem cross-section.

We report a wavelength-scanning-based lensless on-chip microscope using a color CMOS sensor and a matching modified phase retrieval algorithm for pixel super-resolution. Without physically removing the Bayer color filter array positioned on the sensor chip, we demonstrate quantitative phase imaging with a lateral resolution of 615 nm over a wide field-of-view of 51.88 mm² by exploiting the green-channel data from a set of low-resolution holograms captured at various wavelengths. The resulting spatial bandwidth product is 274.3 Megapixels, over 20 times higher than a conventional optical microscope.

The label-free computational techniques with phase imaging capability unfolds the domain of quantitative phase imaging (QPI) to a broad range of microscopy applications. However, the presence of scattering layers in the propagation path makes the conventional QPI approaches susceptible due to the light scattering effects in the medium. Owing to this phase imaging challenge through scattering layers, we propose and experimentally demonstrate a technique for the quantitative imaging through scattering layers by integrating the lens-less digital holographic microscopy with speckle correlation approach. The proposed technique utilizes a holographic compact microscopy scheme for the recovery of phase information of the object located at any arbitrary planes behind the scattering medium by utilizing a correlation hologram and an in-line hologram. The QPI capability of the developed system is theoretically introduced and experimentally validated by imaging various standard and unknown phase samples.

An absolute surface encoder employing a mode-locked femtosecond is newly proposed. The encoder utilizes a variable line space (VLS) grating, whose grating pitch interval varies continuously with its grating position. When the femtosecond laser having a wide range light spectrum is illuminated onto the VLS grating, each wavelength diffracts with a difference diffraction angle. In addition, the diffraction angle of each wavelength changes corresponding to the position of the VLS grating due to the different grating pitch at each position. Therefore, it is possible to measure the absolute position by detecting the diffracted wavelengths by a detector with a designed angle. This paper reports about some basic verification about the feasibility of the proposed absolute surface encoder.

Picometer measurement is a key technology in semiconductor lithography, and the existing methods are difficult to meet the accuracy requirements in large-scale measurement due to inherent error and stability problems. In this paper, we proposed the picometer comb as a new approach for picometer measurement. The exposure period of the interferometric field is measured by the scanning reference grating (SRG) method, the one-dimensional picometer comb is made vertically through double-exposure holography, with a picometer-scale difference in periods between two exposures. We found that it can generate a stable light field distribution with an extremely long depth of field and a small divergence angle, the picometer-scale displacement information can be detected by using the axial Moore interference effect of the onedimensional picometer comb. Picometer measurement technology based on the picometer comb is expected to advance the development of future picometer optical components and technologies.

High-precision position and orientation measurement plays a crucial role in modern engineering and scientific fields, finding applications in areas such as advanced manufacturing, aerospace, and medical technology. Grating encoders are stable and highly accurate position and orientation measurement solutions, particularly well-suited for multi-degree-of-freedom high-precision measurement scenarios.

This paper addresses the modeling and compensation of crosstalk errors resulting from grating angle variations in a previously designed six-degree-of-freedom grating encoder for position and orientation measurement. The six-degree-offreedom grating encoder consists of components such as a light source module, reference and measurement gratings, an angle measurement module, and a displacement measurement module. The deflection of the grating affects the interference signal for displacement measurement. The emitted light beam from the light source undergoes diffraction by the measurement grating, using for measuring three degrees of freedom (angles). The interference between the diffracted light from the measurement grating and the reference grating is detected by the displacement measurement module, using for measuring three degrees of freedom (displacements). The traditional grating displacement measurement does not consider the influence of rotation on the laser phase. This paper innovatively models the influence of rotation on the laser phase, which can compensate the displacement settlement, and the ultra-high precision displacement measurement can be obtained.

In order to solve the problem of the mutual limitations of large measurement range and high precision of absolute grating encoders, this paper employs absolute codes to individually number each spliced grating section on the substrate, leveraging the asymmetric code arrangement. With the light splitting ability of beam splitter, the light source is divided into dual beams and inputted into the encoder to form a dual beam reading head. At least one beam of light can always generate a stable signal within the travel range, and then the serial number of this grating area is determined through absolute codes. The signals generated by gratings with different numbers can be calibrated using calibration parameters. With the help of the data splicing principle and the structure of dual-beam, a nanoscale positioning accuracy scheme with a meter-level measurement range is proposed.

The heterodyne grating interferometer, based on the interference effect of gratings, has achieved widespread applications in the field of high-precision measurements. Its output optical signal, after phase measurement processing, allows for the acquisition of displacement data of the measured object. Among the phase measurement methods, the orthogonal lock-in method obtains two signals containing phase difference information through mixing and filtering. However, the orthogonal lock-in method faces various challenges in practical applications, such as significant sensitivity to filter performance and poor generalization capability. In particular, the need to adjust filter parameters according to changes in the measurement signal frequency limits its practicality and flexibility.

To address these challenges, this study proposes an enhanced lock-in method that utilizes pulse counting techniques to roughly estimate the frequency of the measurement signal and generates orthogonal signals for mixing with the measurement signal. Implementation and experiments on the FPGA platform demonstrate that the improved orthogonal lock-in method can achieve a resolution error of tens of picometers, with a maximum measurement speed exceeding 1 m/s. This research outcome effectively enhances the robustness of the lock-in method, aligning more closely with engineering requirements for high-precision phase measurement.

The grating scale is a high-precision displacement measurement sensor based on the principle of grating optics. Among them, the 1.5D grating scale, as a special type, traditionally relies on relative measurement methods. In this paper, we introduce an innovative concept of an absolute 1.5D grating scale, whose core lies in the addition of labels at both ends of the grating scale. This design utilizing the concept of absolute measurement overcomes the limitations of relative measurement, enabling direct reading of position information without a reference point, thus significantly enhancing overall performance.The grating scale features a large detection range, high precision, and fast response, making it widely used in various fields such as machinery manufacturing, electronic equipment manufacturing, scientific research, and aerospace.

A 2D supercell grating was proposed to work as a polarization beam splitter (PBS) at normal incidence, which directed TE-polarized light to (0, ±1) order and TM-polarized light to (±1, 0) order. The diffraction efficiency of targeted transmitting orders reached 71.32% and the extinction ratio exceeded 19.97 dB for TE- or TM- polarized illumination with 1550nm wavelength. Meanwhile, the (0, 0) order was well suppressed. The proposed 2D supercell grating is suitable for compact polarization systems.

Circularly polarized light is generally generated by linearly polarized light passing through a quarter wave plate, which use the birefringence to generate phase difference. However, two beams of orthogonal linearly polarized light can also produce phase difference after being reflected by the grating. In this paper, two beams of orthogonally polarized light were incident on the one-dimensional grating, and the reflected diffracted light produced a phase difference. When the phase difference of π/2 is satisfied and the amplitudes of the two orthogonal polarized lights are equal, circularly polarized light can be obtained. In this way, multiple beams of circularly polarized light can be obtained, and a simple method for obtaining circularly polarized light has been developed. Adjusting the period, duty cycle and groove depth of the rectangular grating can change the phase of the reflected light. By finding suitable structural parameters, we can design a quarter wave plate grating that can obtain multiple beams of circularly polarized light at the same time. This is a kind of new optical delayed π/2 phase device.

This study designed a large aperture infrared diffraction system that utilizes Schupmann's achromatic theory to achieve wavelength tunable high-resolution imaging. The impact of stitching error on imaging quality was analyzed based on geometric optics, and simulation analysis was conducted on stitching error based on wavefront aberration. The results indicate that the system has reached the diffraction limit of imaging quality in the design band, and both wavefront aberration and distortion are within acceptable ranges. Splicing error analysis shows that translation error has a significant impact on imaging quality, while edge mismatch error and tilt error have a smaller impact. This system has the characteristics of lightweight and low cost, and is suitable for various space observation tasks.

This paper developed a programmable optical device using as a 1D transmissive liquid crystal optical phased array. Unlike reflective devices that require half-reflective and half-transmissive beam splitters in application system, the transmissive structure is more compact, easier to use and exhibits lower insertion losses. The device is based on a fully embedded system, leveraging a touchscreen for human-machine interaction instead of conventional computer-based control, enhancing portability and reducing costs. Programmable functionalities such as beam scanning, focusing, defocusing, and combined focusing/defocusing with scanning have been successfully implemented, which has important potential applications in free space laser communications, electro-optical countermeasure and lidar detection, among others.

Morphology characterization techniques, such as atomic force microscopy (AFM) and scanning electron microscopy (SEM), are widely used by grating device manufacturers. However, AFM suffers from probe wear, limited imaging range, and slow scanning speeds, while SEM can cause surface damage due to electron beam effects, potentially compromising the detection of grating surface details. To address these issues, this study investigates the correlation between the duty cycle of a two-dimensional grating and the (0,0)-order reflection efficiency using rigorous coupled wave analysis (RCWA). The reflection efficiency curve of the (0,0)-order S-polarized probe light is taken as a function of the duty cycle, and a fast, non-destructive optical method for grating duty cycle detection is proposed. By selecting an appropriate incident angle and measuring the (0,0)-order reflection efficiency at S-polarization, the duty cycle of a restricted range of two-dimensional gratings can be determined, providing robust support for predicting the global surface morphology of gratings. This study introduces a novel method for non-contact grating surface topography detection that is simple, efficient, and low-cost. Combined with an ultra-high-precision displacement stage for scanning, this method enables large-area, non-destructive, and accurate grating duty cycle detection, offering significant advantages for practical grating manufacturing.

Dammann gratings, as quintessential beam splitters, have garnered attention due to their compact and efficient lightsplitting capabilities. In the realm of optics, chiral structures can elicit distinct optical responses from left-handed and righthanded circularly polarized light. The advent of metasurface technology has made it feasible to introduce chirality to Dammann gratings. In this article, we propose the concept of integrating chiral structural elements with Dammann gratings. Through theoretical analysis and numerical simulation of the designed chiral structural units, we demonstrate that this structure can effectively achieve selective manipulation of both circular polarization states. By combining the concepts of geometric phase and diffractive phase modulation with the design philosophy of Dammann gratings, we have designed a Dammann grating based on chiral structural units. This design can achieve a uniform 3×3 point array in the far field. The introduction of chiral structures endows Dammann gratings with new properties, offering a novel perspective for the design of devices with polarization-selective characteristics.

The simplified mode method explains the physical processes inside the grating in terms of the Mach- Zehnder interferometer model. There are three modes include mode 0, 1, 2 in grating under second Bragg angle incidence. We report a special case of fused silica grating when its period is close to 1.3 times of wavelength, where the effective refractive index of mode 1 might be equal to mode 2. In this special case, we found that the joint effect of mode 1 and 2 on the diffraction efficiency for -2 order is not accurate entirely, and the diffraction of the 0th order is approaching to the maximum, both with a slight oscillation of efficiency when the depth of grating is increased. This phenomenon by using simplified mode method could help to understand the physics of grating theory.

During the manufacturing process of gratings, the type and location of defects on the grating surface have a very significant impact on the performance of the grating. Statistical analysis of the types, sources and transmissibility effects of large-size grating surface defects is very important of grating manufacturing. This article collects a large amount of surface defect data accumulated during the grating production process. In the experimental and statistical process, we classified the defects on the surface of the large-size reflection diffraction grating development mask as the research object, and using three methods: manual visual inspection, CCD imaging and metallographic microscope observation to classify the surface defects. After analysis, the defects on the grating surface were finally classified into surface covering defects, embedded defects and substrate scratch defects based on the spatial position of the defects on the sample surface. The physical characteristics of different defects and the classification methods of different types of defects were summarized. Statistics were made on the impact of dust, lint, black and white spots, finger marks and other common defects in the grating manufacturing process on grating manufacturing, as well as the causes and patterns of defects. Experimental results show that the proposed statistical results of grating defects are simple and effective in avoiding defects in the manufacturing process of large-size gratings, and the defect types covered can include most of the defect types produced by grating manufacturing. This statistical result is of great significance to evaluating the quality of grating products and tracing the defects of finished products.

As artificial intelligence consumes more and more power than traditional electronic computers, it becomes urgent to find a new optical computing system to calculate the enormous amount of matrix convolution in a parallel and energy-saving way. The naturally high parallelism of photons offers a potential solution for dramatically increasing computer computing power. This paper proposes a parallel optical computing architecture based on the optical shadow-casting method using a Dammann grating. Firstly, using the unique beam-splitting ability of Dammann grating, the convolution kernel is diffracted to the targeted places on the convolution matrix at different angles, which can realize the flexible sliding of the convolution kernel on the convolution matrix. Secondly, the image conjugation of the 4𝑓 system can significantly increase the alignment accuracy, and the convolution kernel of different diffraction orders is located in the specific position of the convolution matrix. Finally, matrix multiplication and addition are further realized by loading matrix information through the light modulator and lens convergence. The system has significant advantages in energy consumption ratio and computing power improvement, and parallel optical computing might be attractive in competition with the traditional electronic computers in some large-scale matrix computing fields.

Due to hardware limitations infrared images typically suffer from low resolution and low signal-to-noise ratio. Multi-frame image super-resolution technology exploits the additional information from micro-displacements in multiple low-resolution images to improve image resolution. In this work, we have designed an adaptive registration and reference-driven spatial attention network(ARRSAN) for multi-frame super-resolution. Additionally, a denoising module is integrated into the registration process to mitigate the impact of read shot noise on the registration and super-resolution processes. Results from three datasets, FLIR, Rafael and SIATD demonstrate the performance of our method, even in the presence of noise.

The fully analytical method has been widely studied for its higher accuracy and efficiency, and the addition of shading rendering can effectively improve the three-dimensional perception of reconstructed images. However, existing fully analytical polygon-based shading rendering methods suffer from high computational complexity and complexity due to the need for additional calculation of the highlight spectrum. Based on previous research, we employ a continuous light and shadow algorithm that uses linear interpolation to decouple the reflection term from the spectrum, meaning that we incorporate the specular component into the calculation of vertex modulus, and separately compute the vertex modulus and the corresponding spectrum values, simplifying the calculation process of existing Blinn Phong lighting models. The algorithm can effectively generate highly realistic holographically reconstructed images with high gloss effects under continuous illumination. It achieves computational efficiency than existing algorithms, without increasing the number of polygons. Simulations and experimental results have verified the effectiveness of our proposed method.

Research on off-axis reflector-based Augmented Reality Near-Eye Displays (AR NED) is advancing. These displays use a single light source, resulting in a narrow Eyebox and Field of View (FOV), but they are lightweight and suitable for long-term use.

Holographic Optical Elements (HOEs) are used to enhance image quality with narrow-bandwidth laser light sources. Adding compensating HOEs can increase the Eyebox when using micro OLEDs with a wide spectral bandwidth. However, achieving a 15mm Eyebox remains challenging without user calibration for interpupillary distance.
This presentation explores increasing the Eyebox in the off-axis reflector AR NED using Holographic multi-configuration, which involves angular multiplexing HOEs at two different angles. The research team designed prototypes and compared models with and without Holographic Multi-configuration.

In conclusion, the study presents a prototype structure using a wide spectral bandwidth uOLED and two angularly multiplexed HOEs to achieve a larger Eyebox.

Acquiring the phase information could significantly enhance the potential of compressed ultrafast photography (CUP) for frontier scientific exploration as well as engineering application. In this paper, we present a novel compressed ultrafast onaxis holographic imaging system that combines compressed ultrafast photography and on-axis holography techniques, to achieve phase measurements in ultrafast temporal resolution. For data acquisition, the laser passes through the dynamic scene to form the object light, and then converges with the reference light to produce a hologram. This hologram is recorded in a compressed snapshot using spatial encoding, temporal shearing and spatio-temporal integration techniques. For image reconstruction, we propose an algorithm combining the plug-and-play generalized alternating projection (PnP-GAP) and FFDNet deep denoising prior. Simulation results validate the effectiveness of our proposed method.

We proposed a modified superpixel method that is capable of complex amplitude spatial light modulation for multi-wavelength simultaneously with a single binary hologram on DMD. We demonstrate it in color holographic display and structured beam generation, by both simulation and experiments. For the holographic display, multiple characters are displayed in different depths as expected, with a relatively low speckle noise. With the high refresh rate of DMD, the method can realize a dynamic flickering-less display. Our research brings the superpixel method into a multi-color regime and will find its applications in various areas.

Metasurface provide a new method to manipulate electromagnetic wave. The geometric phase obtained through rotating meta-atoms is widely used in broadband phase modulation technology. Although utilizing geometric phase modulation of metasurfaces enables flexible control over the response of electromagnetic waves, that is, by constructing specific phase distributions, desired electromagnetic functionalities can be achieved, along with the design of requisite electromagnetic devices. However, due to the inherent spin-locking nature of geometric phases, relying solely on a single-phase modulation method is increasingly unable to meet the application requirements for the integration, miniaturization, and intelligentization of electromagnetic devices. To address the aforementioned challenge, in order to break the spin-locking characteristic of geometric phase, we have realized decoupled design for orthogonal circularly polarized waves based on the composite modulation concept of geometric phase and transmission phase. We designed eight meta-atoms composed of silicon pillars and a substrate. for infrared wavelengths, with adjacent meta-atoms having fixed phase gradient of π/4. Meanwhile, the geometric phase of each meta-atom can cover the range of 0~2π. Subsequently, taking the holography as examples, the decoupled design of orthogonally circularly polarized waves is achieved, and the simulation results verify the feasibility of the aforementioned spin-decoupled regulation mechanism. In conclusion, the above metasurface exhibits excellent ability to regulate electromagnetic waves in the infrared spectrum. This research has potential application prospects in the fields of infrared communication, imaging, and others.

The accelerated advancement of micro-electro-mechanical systems (MEMS) and microelectronic integrated circuits has led to a growing necessity for the dynamic detection and performance assessment of micro-nano sensors. Digital holography is a highly precise non-destructive measurement method that is capable of meeting the detection requirements of a range of parameters in both dynamic and static conditions. This paper presents a new method for measuring the dynamic parameters of MEMS mirror using a combination of digital holography and event cameras. By analyzing the full hologram recorded by the event camera of the MEMS mirror at a specific time sequence, the vibration frequency of the mirror can be obtained. Under identical experimental conditions, the vibration frequency that can be measured by the event camera is several times to several tens of times higher than that of a general high-speed camera, and it exhibits superior anti-interference performance.

The results of thermochemical laser writing on bi-layer Si/Ti, Si/Zr, Si/Hf films and single-layer Cr film are presented. Silicon capping layer on top of Ti, Zr, Hf metal films protects them from oxidation in atmosphere and increases optical absorption. It has been shown that the thermochemical effect leads to a significant increase in the reflectance in the exposed areas and makes it possible to produce grayscale structures on mentioned-above materials. Bi-layer Si/Ti, Si/Zr, Si/Hf films make it possible to form directly reflective patterns without etching. In addition, there is a significant increase in the optically measured profile depth between the exposed areas and the original bi-layer film. This effect can be used for one-stage technology for direct laser writing of reflective amplitude-phase diffractive structures on these bilayer materials. Writing on Cr film allows to get larger reflection and transmission change but requires etching.

The results of the development of an algorithm for monitoring long-term instability of scanning laser writing systems in the manufacture of diffractive optical elements are presented. To implement the proposed algorithm, special microgratings of two types (2D calibration diffractive marks (2D-CDM) and 2D diffractive sensor elements (2D-DSE)) are built into the working structure of the element, and control is carried out by analyzing the diffraction efficiency of these structures. It is shown that to control the long-term instability of the coordinates of the diffraction zones formed on the substrate, as well as the height and duty cycle of the written structures, it is sufficient to measure 5 diffraction orders for 2D-CDM and for 2D-DSE. An algorithm for writing embedded 2D microgratings and analyzing the measured values of their diffraction efficiency is presented to obtain the corresponding data on errors in writing the working structure of the DOE.

Optical scanning cryptography (OSC) has garnered considerable attention because of its ability to acquire an incoherent hologram from a physical object using a single-pixel sensor. In this paper, we generate a new type of scanning pattern, named light spring (LS), using the two-pupil optical heterodyne scanning system. The light spring, which is characterized by helical structures for their phase and intensity profiles, can be built on the superposition of two distinct laser frequency components. An optical scanning cryptography scheme based on LS is proposed. The scheme expands the temporal characteristics of orbital angular momentum (OAM) multiplexing and improves the encryption capability, key space and security of the system.

Due to the rapid development of information technology, the demand for data storage is gradually increasing. People urgently need a storage technology with large capacity, high speed, and low energy consumption to alleviate the storage pressure brought by current data growth. Collinear holographic data storage system has the advantages of high storage density, system stability, simple structure, and miniaturization, which becomes a research hotspot for the new generation of storage technology. Among them, holographic storage materials are the key to improve the performance of holographic storage technology, and the lifespan of storage materials determines the security, integrity, and accessibility of data. However, traditional recording pattern is sensitive to the recording position due to strict bragg condition. It is difficult to accurately locate the recording position when the material is put back in the system after aging experiment. We design a positioning map to help quick locating. The displacement selectivity of the positioning map is poor, which is easy to find in a large range, and the positioning map pattern can be exposed for a long time without disappearing. The polymethyl methacrylate (PQ/PMMA) photopolymer materials doped with phenanthraquinone was tested on the collinear holographic data storage system. The low bit error rate of the material reading data page proved that the design scheme was feasible, and provided a basis for the follow-up study of material life.

Dark reaction is a common phenomenon in holographic recording of photoinduced polymer materials, which has some influence on the recording effect of materials. Now we design an experiment to prepare polymethyl methacrylate materials doped with different phenanthrene quinone (PQ) concentrations, and observe their changes in bit error rate, signal-to-noise ratio and diffraction intensity after dark reaction. The results show that the higher the concentration of PQ doping, the higher the diffraction intensity after dark reaction, but too high concentration will lead to the increase of bit error rate and signal-to-noise ratio decrease. It is proved that the material with 1wt% of PQ doping concentration also has lower bit error rate, higher signal-to-noise ratio and relatively higher diffraction intensity after dark reaction.

The tight contact of the mask and the substrate is essential in contact lithography for reducing unnecessary diffraction and improving the resolution. This enables contact lithography to reach sub-micrometer resolution and thus shows a great prospect of fabricating arrayed sub-micrometer structure. However, the direct contact of the mask and the substrate and the pressure between the mask and the substrate may lead to the deformation of the photoresist film or the substrate, and affect the micro-structure on the photoresist layer. Therefore, it is necessary to verify whether the change of the pattern size of micro-structure caused by the deformation of the photoresist film and substrate is within the allowable error range.

This paper takes the silicon wafer spin-coated with S1805 photoresist as the research object, and conducts static pressure experiments and interference exposure experiments. Within a pressure of 300 kPa, there is little variation in the thickness of the photoresist film, and it has no significant effect on the pattern size on the photoresist layer. The result shows that when fabricating arrayed sub-micrometer structures, the change of the pattern size of micro-structure is within the allowable error range. Therefore, this paper demonstrates the theoretical feasibility of contact lithography with the pressure in the fabrication of arrayed sub-micrometer structures.

Deep learning provides an efficient and feasible solution for computer-generated holography (CGH), and learning-based CGH shows great potential in realizing real-time and high-quality holographic display. However, due to the difficulty of convolutional neural networks (CNNs) in learning cross-domain tasks, most existing learning-based algorithms still struggle to produce high-quality holograms. Here, we propose a diffraction model-driven neural network (M-Holo) that uses multi-scale frequency domain loss to train network parameters to produce high-quality phase-only holograms(POHs). M-Holo embedded multi-receptive-field (MRF) modules into complex amplitude-generating network encoders designed to improve the receptive field of neural network. In addition, the multi-scale frequency domain loss (MSFL) is also increased in the training process of M-Holo, and the abstract feature of multiple levels of the target image are learned in the frequency domain, which further restricts the spatial domain loss insensitive information. The generalization effect of M-Holo is verified by numerical simulation and optical experiment of grayscale and 3D images. M-Holo can effectively improve the quality of reconstructed images and suppress image artifacts.

The radially polarized vortex beams with excellent focusing characteristics, provide a useful tool for the self-assembly of chiral nanostructures of nanoparticles. Here we presented a simple method for producing cylindrical vector vortex beams. This technique involves converting linearly polarized scalar vortex beams into cylindrically polarized vector vortex beams without the need for strict dual-optical path alignment. The phase hologram loaded onto the spatial light modulators is newly designed to generate linearly polarized vortex beams with different topological charges, concentrating the energy mainly on the first-order diffractions and significantly increasing the energy utilization. Then, the generated beams are introduced to vector polarization using a q-plate to produce radial or azimuthal vector vortex beams. We prepared an AuNPs growth solution comprising CTAB (50 mM, 21.08 mL), HAuCl4 (20 mM, 140 μL), and AA (100 mM, 0.653 mL). SEM images and circular dichroism spectra of the AuNPs exhibit strong chiral nanostructures (L/D-PX AuNPs). We believe that the cylindrical vector vortex beams generated by this method can provide a useful tool for the self-assembly of chiral nanostructures, super-resolution microscopy, optical trapping, and more.

In the present work, we investigate the multiple plane phase retrieval (MPPR) algorithm which addresses the issue of missing center in diffraction patterns, which results from saturation due to the use of a detection system with a limited dynamic range. Using an extrapolation technique in saturated areas, we algorithmically overcome this hardware constraint associated with the restricted dynamic range of the detection system. The validation of the proposed phase retrieval method is conducted on a dataset captured in the terahertz (THz) region, which contains overexposed areas. We compared the reconstructed amplitude and phase distributions obtained from incomplete data with reference images obtained using a conventional algorithm when processing a high dynamic range (HDR) dataset. The algorithm’s convergence was examined when processing datasets with different levels of noise and saturation. Phase retrieval is shown to be possible even if 90−94% of the total energy of the beam is compromised by saturation in recordings, and at a low signal-to-noise ratio (SNR) near 6. Our proposed method effectively addresses the limitation associated with the insufficient dynamic range of the receiver, significantly simplifying data acquisition compared to HDR registration. For the first time, we demonstrate the application of MPPR to address the issue of data saturation and show the feasibility of retrieving the wavefront using only information from the high-frequency diffraction components while extrapolating the missing center information.

Metasurfaces present novel prospects for compacted quantum technologies by providing precise manipulation of amplitude, phase, and polarization of the incident light. Utilizing the advanced polarization control and multiplexing capabilities of metasurfaces, the capacity for detecting and processing quantum information can be enhanced. In this work, we optimize metasurface fabrication using electron-beam lithography and develop a custom SEM image recognition program for precise structure assessment and improved imaging quality. We achieve holographic imaging under quantum state incidence, enabling the reconstruction of quantum state information from the resulting meta-holography.

High-speed imaging of large numbers of biological samples is critical in numerous biomedical applications. Conventional methods can usually only image a single sample, and for a large number of samples, they can only be imaged sequentially. Here, we propose a dual-plane phase retrieval (DPR) method in the lens-free on-chip microscopy system (LFOCM) based on partially coherent light-emitting diode (LED) illumination. Unlike previous methods, we stack two samples in the axial direction and image both layers simultaneously. Using only five coaxial holograms recorded by the sensor, the phase information of the two layers of stacked samples (including a phase resolution target and a HeLa cell sample) illuminated by LEDs, can be accurately recovered in a large field of view of 19.53 mm² without compromising their resolution. We quantitatively verified the effectiveness and accuracy of the method in simulations and experiments. The proposed method provides a solution for efficient sample handling in lens-free on-chip microscopy.

Miniaturized spectrometers, owing to their compact dimensions, high sensitivity, and low cost, have been extensively applied in environmental monitoring, biomedical diagnostics, industrial inspection, and other fields. However, conventional miniature spectrometers often face challenges in simultaneously achieving high spectral resolution, miniaturization, and a high degree of integration. As a pivotal component in integrated optics, the Arrayed Waveguide Grating (AWG) possesses advantages such as exceptional resolution, broad spectral bandwidth, and superior integrability, thus serving as a highly effective means for the design and realization of miniature spectrometers. Here, a highly uniform visible light arrayed waveguide grating with a central wavelength of 633nm was designed and fabricated. The device was based on a 300 nm silicon nitride platform, with the waveguide width of 300nm. The beam diverges at the input star coupler, then propagates through the arrayed waveguide, and finally converges on the image plane of the output star coupler. There are 4 output channels with a channel spacing of 10nm, and the spectral resolution is 5nm. This configuration can provide a uniform spectral output with a high stability, making it suitable for applications in the field of spectral analysis.

Lens-free on-chip digital holographic microscope (LFOCDHM) is crucial for biomedical applications like cell cycle assays, drug development, digital pathology, and high-throughput biological screening. The unit magnification configuration results in a field-of-view (FOV) containing over a hundred times more cells than a conventional 10× microscope objective, making segmentation labor-intensive and time-consuming due to complex and variable cell morphology. Although many deep learning-based cell segmentation methods exist, convolutional neural networks (CNNs) have a limited localized receptive field and are unsuitable for large FOV imaging from LFOCDHM. We propose Swin Transformer U-Net (STU-Net), a high-throughput live cell analysis method. It uses a shift window to compute self-attention and extract features at five scales, achieving accurate cell segmentation (accuracy > 0.9743). We validated STU-Net’s robustness and generalizability with HeLa cell slides across the full FOV in vitro. This approach, capable of quantifying cell growth and proliferation from segmentation results, offers a strong foundation for drug development and biological screening.