Current hologram computation suffers from low efficiency and loss of encoded information. To address these issues, a novel encoding method for complex amplitude hologram is proposed. The proposed approach decomposes the complex amplitude distribution calculated by the angular spectrum method into amplitude and phase information, then generates a hologram containing complete amplitude and phase information through multi-phase encoding. Compared with the traditional Gerchberg-Saxton （GS） algorithm, under the same computation time, the proposed multi-phase encoding method improves the PSNR of the reconstructed holographic image by 15.49 dB and the SSIM by 0.65. This method provides a new approach for enhancing the quality of holographic reconstructed images for three-dimensional display.

To enhance the detection efficiency of structured vortex beams carrying Orbital Angular Momentum （OAM）, a recognition method combining deep learning with FPGA acceleration is proposed. Random phase screens are generated using the power spectrum inversion method, and five types of atmospheric turbulence conditions are simulated via a spatial light modulator. Vortex beam spot images after passing through the random phase screens are collected to construct a dataset comprising 10,000 samples. A ResNet18 Convolutional Neural Network （CNN） is employed to analyze and compare the impact of different turbulence intensities on OAM mode recognition accuracy. The recognition performance of the model is comprehensively evaluated, and the trained ResNet18 model is subsequently deployed onto a Field-Programmable Gate Array（FPGA） hardware platform for real-time OAM mode recognition. Experimental results demonstrate that under weak and moderate turbulence conditions, the recognition accuracy for three OAM modes reaches 100%, while under strong turbulence, the accuracy for two OAM modes remains as high as 99%, showing a slight decrease compared to the weaker turbulence cases. By deploying the CNN model onto the FPGA platform, the system achieves an energy consumption of 2.844 W, an energy efficiency of 2.19 GOPS/W, and an inference time of 0.58 seconds for OAM mode recognition of vortex beams.

With the increase in transmission rate and transmission distance, the impact of nonlinear impairments on the performance of long-haul fiber-optic communication systems becomes increasingly significant, severely restricting overall system performance. In order to mitigate integrated effects of nonlinear impairment for the long-haul fiber-optic communication system, a dual-branch hybrid neural network-based nonlinear impairment compensation method for the long-haul optical communication system is proposed. Firstly, the channel memory is leveraged by the model to capture the global feature of channel impairments in the time domain, so as to optimize feature learning of current symbols through historical information; Secondly, the spatial features of symbols in the constellation diagram are captured by the real-valued branch based on convolutional neural networks, and the channel attention mechanism and the spatial attention mechanism are adopted to enhance the learning capability of the model for nonlinear impairment-related spatial features; Finally, the latent information of phase and amplitude variations of complex symbols is captured by the complex-valued branch, thereby the combined effects of nonlinear impairments are effectively compensated. Numerical simulation is established with self-phase modulation and cross-phase modulation as the primary nonlinear effects, simulation results demonstrate that the proposed method achieves a lower bit error rate and exhibits stability under varying conditions of transmitted optical power, transmission distance and symbol rate.

The extreme ultraviolet lithography objective with a numerical aperture of 0.33 is composed of 6 high-order aspheric mirrors. However, the objective system containing large-aperture aspheric mirrors has more stringent requirements on processing and detection accuracy. A design method for hybrid surface optimization is proposed. Small-aperture aspheric mirrors are replaced with free-form surfaces one by one using the interactive iterative optimization technology of free-form surfaces and aspheric mirrors. The high-order coefficients of large-aperture mirrors are effectively reduced, and the aspheric coefficient of the largest-aperture mirror is reduced from 16th order to 10th order. The difficulty of objective processing and detection is significantly reduced. A set of NA 0.33 hybrid surface extreme ultraviolet lithography objective system was designed using this method. The distortion value of the objective system is less than 0.294nm, and the root mean square value of the wavefront error is less than 0.0143 （=13.5nm）. By selecting the compensator by the inverse sensitivity method, the tolerance of the objective system is improved by one order of magnitude. At a cumulative probability of 97.7%, the wavefront error RMS is less than 0.037, and the stability of the lithography objective system is further improved.

In order to explore the morphology of molten pool and the distribution of temperature field in the process of laser additive manufacturing on the surface of aluminum alloy plate, a three-dimensional finite element model of fluid heat transfer was established. Considering the thermophysical properties of the material during processing and the change of laser absorption rate with temperature, the effects of laser power and scanning speed on the flow field and temperature field distribution of the molten pool were studied. The results show that in the process of processing, the morphology of the molten pool will be affected by gravity, recoil pressure and Marangoni effect. Larger laser power and lower scanning speed can make the molten pool have higher temperature and larger size, but it is easy to cause splashing of the metal liquid in the molten pool, which affects the processing quality of the material. Smaller laser power and higher scanning speed will lead to insufficient energy of the material to absorb the laser and cannot be fully melted, which is prone to spheroidization. When the laser power is set at 86 W and the scanning speed is set near 1300mm/s, the parts can obtain good forming quality. This study provides a certain theoretical and data reference for laser additive manufacturing of 6061 aluminum alloy.

Digital Polymerase Chain Reaction （dPCR） is a molecular biology technique that enables absolute quantification. However, conventional dPCR fluorescence detection systems face challenges in achieving an optimal balance among detection throughput, speed, system size, and cost. In particular, traditional illumination system designs are constrained by limitations in illumination area, uniformity, volume, and switching response, which affect the overall performance and applicability of the equipment. To address these issues, this study proposes a portable dPCR fluorescence detection system optimized for large-field imaging based on an LED excitation design with uniform illumination. This system aims to reduce size and costs without compromising detection speed and throughput. Utilizing a high-integration ring-shaped LED light source arrangement, the system achieves uniform illumination across an 18 mm × 18 mm field of view for three fluorescence channels（FAM, HEX, ROX）, with actual illumination uniformity exceeding 90%, and supports rapid three-channel switching.Compared with traditional illumination modules, the LED-based uniform excitation illumination offers advantages in miniaturization, cost-efficiency, and integration, making it suitable for various fluorescence detection applications and advancing the future development of dPCR technology.

F-P optical resonant cavity （Fabry-Prot cavity） is widely used for sensing refractive index, temperature,pressure, etc. The closed fiber F-P resonant cavity limits the types of substances to be measured and their measurement range due to the long resonant cavity. Herein, a short cavity length open F-P refractive index sensor was designed and fabricated based on thin film technology and lithography , which definitely increases the measurement range and high sensitivity,and is suitable for gases and liquids. Theoretical research was conducted on the influence of mirror reflectivity and cavity length on the sensitive parameters of open F-P cavity, and an open F-P resonant cavity structure and characteristics were all determined, including upper and lower high reflectivity mirrors （99.7%） and short cavity length（3.305 m）. The FDTD simulation results showed that its free spectral range was as high as 42nm, the sensitivity was as high as 385.85nm per Refractive Index Unit（RIU）, and the refractive index measurement range was one order of magnitude higher than traditional F-P cavities, reaching to 0.129RIU. In addition, a refractive index testing and verification system was built, and refractive index testing experiments were all carried out. Experimental verification showed that the greater the change in refractive index, the greater the shift in the center wavelength. The average change in the center wavelength was 1.79 nm/RIU, and the experimental sensitivity was determined to 346.65 nm/RIU. The results lay a theoretical and practical foundation for low-cost,wide measurement range, and high-precision liquid/gas refractive index sensors.

Compared with the traditional optical fiber sensing technology, Brillouin dynamic grating （BDG） has the advantages of multi-parameter simultaneous sensing and high measurement accuracy. At present, the research on BDG indicators is mainly based on the different types of BDG and BDG generated in different optical fiber media. There are four types of BDGs based on different types: chirp, phase shift, random and chaos. While chaotic BDG achieves high-precision and high-spatial resolution measurement, it can achieve a single, stable dynamic grating to overcome the influence of multiple gratings and its limitations in distributed optical fiber sensing. BDG generation media include single-mode fiber, few-mode fiber,polarization-maintaining fiber and photonic crystal fiber. Compared with other optical fibers, photonic crystal fiber has high birefringence coefficient and can improve the sensing distance. Firstly, the principle of BDG is introduced, and the application and research progress of chaotic BDG and photonic crystal fiber are reviewed in detail. At the same time, the application of BDG in multi-parameter simultaneous sensing, high-precision measurement and high spatial resolution in distributed optical fiber sensing is introduced. Finally, some problems in this field are discussed.

To meet the requirements of continuous laser power measurement,a specialized energy collection system for continuous spectrum lasers is desighed, which is capable of high-precision detection of energy distribution in the wavelength range from 0.4m to 2.4m, with multiple output channels and extremely high repetition frequency. The system uses a thermopile detector with copper oxide as the absorption layer, combined with signal processing techniques, and implements dynamic response and precise resolution of wide-spectrum laser energy using a weighted sliding mean filter algorithm. Through energy calibration for the 671 nm and 1064 nm bands, the system can provide stable measurement results under complex spectral conditions. Experimental results show that the measurement error between the system developed using this approach and the standard laser power meter is within ±1.5%. This result demonstrates the feasibility of measuring a continuum laser energy system.

Poisson Superfish and General Particle Tracer were used to simulate UED DC photocathode electron guns with different magnetic shielding plates. The smaller the center hole of the magnetic shielding plate, the better the magnetic field shielding. The shielded magnetic field is proportional to the aperture radius. Continuing to reduce the hole does not significantly improve shielding, while the central hole is too small. The thicker the magnetic shielding plate, the better the shielding effect, but the improvement is not significant. The shielded magnetic field is inversely proportional to its thickness.The closer the magnetic shielding to the electron gun, the larger the field in the gun, which mainly due to magnetic leakage from the central hole. The shielded magnetic field is inversely proportional to the distance from the cathode. The installation of magnetic shielding plates leads to premature focusing of electronic pulses and a smaller focusing radius. The smaller the center hole in the magnetic shielding plate, the smaller the focusing radius and focal length. The thicker the magnetic shielding plate, the smaller the focusing radius and focal length. The farther the magnetic shielding plate to the electron gun, the smaller the focusing radius and focal length. The better the magnetic field shielding , the smaller the magnetic field between the electron gun and the magnetic shielding, and the smaller the electron pulse focusing radius and focal length

The transmission characteristics of cascaded Bragg grating with defect layers have been studied by simulation.The results show that the resonance peak of the filter increased with increases of the number of cascaded defect layers. The number of cascaded defect layers was the same as the number of resonance peak. And the Bragg grating with seven defect layers have seven resonance peaks. As the number of cycles between defect layers and the length of defect layers increase, the resonant wavelength undergoes center shift and red shift, respectively. Under different defective layer lengths, the maximum resonance wavelength changes rate of the Bragg grating with single, double, and triple defect layers was 0.0477, 0.03021,and 0.03107, respectively. And the number of cycles at the input and output terminals can helps to control the transmittance of the filter. According to the simulation results, the applicable multi-wavelength filter can be obtained by optimally designed the related parameters of defect layers.

In this study, a high-resolution spectrometer with a multi-fiber array input design is proposed to address the issue of weak Raman-scattered light detection energy caused by insufficient image plane utilization in conventional spectrometers that use a single optical fiber as the incident light source. The design optimizes the optical path by arranging seven incident optical fibers along the sagittal direction of the slit and incorporating a cylindrical lens for astigmatism correction. The system employs a 785 nm excitation wavelength and achieves a broad spectral coverage of 170~3200 cm-1 across seven fields of view, achieving a full-band resolution of 7 cm-1. Experimental results demonstrate that, compared to the 72% image plane utilization achieved with a single fiber configuration, the proposed design—featuring clustered fibers combined with a cylindrical lens significantly improves the image plane utilization to 97%, while maintaining uniform energy distribution across the image plane. This solution offers an effective approach for applications demanding high energy detection efficiency and intensity.

The moisture absorption behavior of resin lenses can cause time-dependent performance issues of the lenses.Under specific temperature and humidity conditions, the performance of the lens is in a dynamic state of change. The primary reason is that the lens absorbs moisture, generating hygroscopic stress, which causes the surface shape of the lens to deform,thereby affecting overall optical performance. To solve these problems, there are two improvement directions. Scheme one is to optimize the optical system to reduce the surface shape sensitivity, but for specific optical specifications, the adjustment space is very limited. Scheme two is to shorten the duration of the time-dependent performance and quickly restore the system's time-dependent performance. Shortening the dynamic change time requires the analysis and simulation of the moisture absorption behavior of resin lenses, and studying the relationship between the lens structure and the moisture absorption equilibrium time to provide a direction for the design of the optical system scheme. The water absorption characteristics of resin lenses fivst experimentally is tested. The results show that temperature and humidity have a significant impact on the moisture absorption rate and saturation water absorption rate. Based on the experimental data and Fick's model, a moisture absorption model of resin lenses was established and verified. Finally, the relationship between the lens structure parameters and the moisture absorption equilibrium time was studied. The results show that the specific surface area of the lens is inversely proportional to the moisture absorption equilibrium time. The larger the specific surface area, the shorter the moisture absorption equilibrium time, and the shorter the dynamic change time of the lens performance.

A domestic tunable external cavity diode laser based on Littrow configuration is designed and constructed,aiming to advance the localization of high-performance lasers and meet the demand for high-quality light sources in fields such as precision spectroscopy and fiber optic sensing. All optical components of this laser are made in China. A compact mechanical structure is designed based on the parameter characteristics of each component. After the completion of the construction,the laser was debugged and optimized to improve the beam quality. The Littrow tunable external cavity diode laser operates in a single longitudinal mode, with a central wavelength of 1580 nm, a maximum wavelength tuning range of 74.06 nm, a tuning speed of 261.256 nm/s, a coherence length of more than 37.5 m and a linewidth of less than 8MHz （0.064 pm）.

Polydimethylsiloxane （PDMS） optical waveguides have a wide range of biomedical applications due to their excellent biocompatibility. In order to improve the refractive index of PDMS to improve the application limitations of PDMS optical waveguides, PDMS-TiO2 organic-inorganic nanocomposites were prepared by in situ sol-gel method using terminal hydroxyl polydimethylsiloxane （PDMS-OH） and titanium tetramethoxymethane isopropoxide（TTIP） as the main raw materials. By changing the mass ratio of PDMS-OH to TTIP, uniform and transparent PDMS-TiO2 solutions with different refractive indices were obtained, and the refractive indices of the materials were characterized by ellipsometry after the curing of the solutions into films, and the refractive indices were increased from 1.40 to 1.591 at 589 nm. Using the soft embossing technique, the core and cladding layers of waveguides were made of PDMS-TiO2 and PDMS, respectively. A flat plate-type multimode waveguide with a cross-section of 5 cm × 80 m was prepared, and the average transmission loss was measured to be 0.713 dB/cm when the input wavelength was 633 nm.This study provides a new reference for the application of PDMS optical waveguides in biomedical fields.

Three-dimensional confocal Raman spectroscopic imaging is widely used in materials science and biomedicine due to its unique molecular selectivity and non-destructive, in-situ analytical capabilities. However, its inherent limitation of inadequate geometric resolution hinders the development of more advanced applications. In this study, a super-resolution mapping method that employs a Residual Dense Channel Attention Network （RDCAN） to transform 3D confocal Raman spectral images into geometric topography is proposed. An end-to-end deep learning model is designed based on a Residual Dense Network （RDN）, which effectively integrates both local and global multi-scale features. The model incorporates a channel attention mechanism to dynamically optimize feature weight allocation, thereby enhancing feature extraction capability. A self-developed laser differential confocal Raman spectroscopy system is used for data acquisition. In this system, 3D spectral data obtained by the confocal Raman module serve as input to the network, while the geometric topography data captured by the differential confocal module serve as ground truth for training. The reconstruction of geometric topography is ultimately realized. Experimental results show that the reconstructed geometric topography achieves a peak signal-to-noise ratio（PSNR） of 27.4dB and a structural similarity index （SSIM） of 0.98, closely matching the measurements obtained by differential confocal microscopy. Compared with traditional methods, the proposed approach enhances high-resolution geometric imaging based on conventional 3D confocal Raman spectroscopy without requiring additional hardware. It also enables spectral-geometric homologous fusion, offering an innovative solution to overcome the limitations in geometric resolution.

Phase-sensitive optical time-domain reflectometer （-OTDR） requires extremely high sampling frequency because it mostly adopts the coherent detection method. In order to reduce the sampling frequency of the system, a frequency-shifted dual pulse modulation direct detection -OTDR system is proposed. The frequency-shifted dual pulse light with frequency shifts of 79 MHz and 81 MHz, respectively, was generated by the time-delay frequency conversion control of the acousto-optic modulator to modulate the Rayleigh backward scattering signal onto the sidebands with a heterodyne frequency of 2 MHz. And the system sampling frequency is reduced to 10MHz by combining with the heterodyne demodulation technique. The validity of the frequency shift is verified by using the Mach-Zehnder interferometer structure, and the accurate demodulation of the vibration signals of 200Hz, 500Hz, 1000Hz, and 2000Hz is successfully realised at the sampling frequency of 10MHz. In the repeatability experiment, the linear fitting coefficient reaches 0.9989, which verifies the stability of the system for vibration signal demodulation under low sampling frequency conditions, and provides an effective technical solution to reduce the hardware cost and data processing capacity of the -OTDR system.

Fringe projection profilometry is one of the most effective methods to obtain the three-dimensional （3D） shape of objects. However, when measuring highly reflective objects, more fringe images need to be projected, and the accuracy is not high. Therefore, a method for measuring the 3D shape of highly reflective objects based on adjusting projection intensity is proposed. First, the optimum projection intensity is calculated according to the surface coefficient of the object. Then, the coordinate correspondence between camera and projector is calculated according to the polar constraint and phase information,and the adaptive fringe is generated. Finally, the adaptive fringes are projected onto the surface of the object under test to achieve three-dimensional measurement of the object. The experimental results show that when measuring the steps of high reflective surfaces, the maximum absolute error is 0.0249 mm, which is 97.8% less than the method of single projection intensity, 18.6% less than the existing method of adjusting projection intensity, and the number of projected images is reduced by 18. The proposed method can reduce the number of projection fringes and improve the measurement accuracy.