Ultrafast laser can achieve extremely high power in an extremely short time, revealing the extreme interactions between light and matter. They possess advanced material processing capabilities and are ideal driving sources for generating extreme ultraviolet (XUV) and high-order harmonic (HHG) pulses, with broad application prospects in medical diagnostics. Since its inception, the titanium sapphire (Ti:Sa) laser has been a mainstream direction in ultrafast laser research, with pulse widths easily reaching below 50 fs. However, the average power has been limited to a few watts, which restricts its application in broader fields. The post-compression technology, with the introduction of multi-pass cell (MPC) nonlinear pulse compression technology, the combination of ytterbium-doped crystal lasers and MPC nonlinear pulse compression technology, has gradually developed into a promising solution for generating high-power ultrashort pulses. This has yielded impressive results, making it possible to achieve average powers exceeding several kilowatts and single pulse energies. The basic principles of MPC are mainly introduced, the latest research progress in MPC nonlinear pulse compression technology is reviewed, and the future development directions and cutting-edge applications of this technology are pointed out.

In the process of laser communication, due to the vibration of the satellite platform, the noise of the mechanical turntable, etc., there will be random angular jitter between the incident optical axis and the receiving optical axis, which affects the performance of the communication system. The effect of random angular jitter on the coupling efficiency of spatial light to single-mode fiber is studied. A closed-loop compensation system based on charge coupled device (CCD) camera and fast tilting mirror is proposed. The experimental platform is built in the laboratory to test the influence of different jitter amplitudes on the coupling efficiency of single-mode fiber, and the feasibility of the compensation system to improve the coupling efficiency is verified. Experimental results show that the closed-loop compensation system can increase the coupling efficiency by 24%. At the same jitter frequency, the compensation effect is more obvious when the jitter amplitude increases. The compensation system compensates for low-frequency jitter more effectively than the high-frequency. These studies provide data reference and technical support for solving the effect of random angular jitter on the coupling efficiency of single-mode fibers.

Dual-wavelength lasers have significant applications in differential absorption laser radar (DIAL) and other areas. A dual-wavelength laser output of 1 047 nm&1 064 nm is achieved by pumping neodymium-doped lithium fluoride Nd:YLF and neodymium-doped yttrium vanadate Nd:YVO4 crystals with rubidium laser pumped by semiconductor laser. And the feasibility of achieving dual-wavelength output of this technical route is verified. When the power of the semiconductor laser is 16.05 W, the total laser power of the dual wavelength is 102.8 mW, the slope efficiency is 1.27%, and the power ratio of two wave is 404:1, which provide a new technical way for the generation of dual-wavelength lasers.

The principle of pulse division and temporal coherent combination is introduced. The system of temporal coherent combination of short pulses is designed, and the experimental research platform is established. By employing a series of polarization beam splitters, delay lines and wave plates, each pulse with repetition rate of 10 MHz and pulse duration of 1 ns can be divided into four-pulse, whose interval is 2 ns. The divided pulses can be recombined using similar polarization beam splitters, delay lines and wave plates. Through adjustment of polarization and optimization of the amplitude distribution in divided pulses, the temporal coherent combination of four pulses has been obtained, and the combination efficiency is up to 95.65%.

Detecting the ground image quality of aerial cameras is an important characteristic for their performance testing. Whether the aerial camera ultimately meets the design requirements needs to be verified through actual aerial photography, the ground target detected by aerial photography is not an actual ground target, but a manually setting target. At present, there is no corresponding technical standard and quality evaluation system for this type of target in China. Resolution detection of three line target imaging is a commonly used, intuitive, easy to read and quantitative discrimination method for evaluating ground image quality using aerial cameras in China. The different expressions of ground resolution and the composition of three line targets are briefly described. The relationship between ground resolution of three line targets and altitude, focal length are analyzed. According to the characteristics of three line target resolution discrimination methods, and incorporated with practical applications, a three line target for aerial photography experiments is designed. And the aerial photography results meet the performance requirements of the designed aerial camera ground resolution aerial photography technical characteristics.

A new type of hollow-core anti-resonant fiber (HC-ARF) with single-mode, broadband and good bending characteristics is proposed for the fabrication feasibility by adding a connecting tube outside the cladding tube of six-tube nested HC-ARF, and the fabrication is completed based on the constructed virtual preparation model. The virtual fabrication model is established on the improved six-tube nested HC-ARF to complete the optimization exploration of the fabrication process and the influence of the control deviation of the fabrication process parameters on the operation characteristics of the fiber is discussed. The fabricated fiber has shown a high-order mode extinction ratio (HOMER) of more than 100 at a wavelength range of 1.40~1.65 m with a bandwidth of 250 nm, which can maintain single-mode transmission with a total loss of less than 0.2 dB/km, the minimum loss of 0.01 dB/km is at a wavelength of 1.50 m and the most HOMER is as high as 2 626, the bending loss is less than 0.4 dB/km at a radius of no less than 10 cm. Fabrication analysis results show that the proposed HC-ARF has good broadband single-mode operation characteristics and robustness to the effects of the fabrication process parameters. The results are of great significance for the innovative design of HC-ARF structure and the development of fabrication technology.

In order to meet the requirements of the processing speed in real time of electro-optical images, a signal processing system based on multi-core DSP and FPGA is designed. And the hardware and software architecture design of this system is introduced. Images are transmitted by optical fibers and can be used to process CCD image data in different optical bands. Taking a fire monitoring system based on visible light CCD sensor as an example, utilizing the characteristics of flames and smoke during object combustion, and the image feature extraction algorithm is used to process the collected images in real time. After identifying the fire area, it is reported. Experimental results show that the signal processing system works reliably and stably, and has the ability of high-speed parallel image processing, which can simultaneously process multiple CCD images, achieve software online loading, image storage and unloading functions, and provide a universal solution for the system platform of electro-optical image processing.

Terahertz (THz) technology has received increasing attention from researchers worldwide in recent years, especially regarding efficient dynamic modulation devices for THz waves. A hybrid THz metasurface modulator combining monolayer graphene with a dual-metal ring electromagnetically induced transparency (EIT)-like structure is proposed, capable of modulating the EIT-like effect and possessing the advantage of polarization insensitivity. The electromagnetic properties and modulation capability of this modulator device are analyzed through simulation. The results indicate that the dual-mode EIT-like structure forms an EIT peak at 0.565 THz with a transmission of 0.66. Under the modulation of graphene, the modulation depth of the hybrid metasurface EIT peak transmission reaches 44.9%, and the group delay modulation depth reaches 22.8%. Simulation results validate the effectiveness of the hybrid metasurface for modulating EIT-like effects. This hybrid metasurface modulator holds promising applications in THz communication, slow-light modulation, and other fields.

An efficient and convenient pneumatic device that meets the consistency requirements of batch product assembly is designed, involving the field of mechanical assembly fixtures and being applied to the three-point mechanical limit assembly of components. A new pneumatic device is designed based on a three claw pneumatic chuck using three dimensions modeling software. By designing the assembly dimensions of the overall structure of the component, precise positioning in the Z-axis direction of the space between the two components can be achieved, while a three-point uniformly distributed limiting assembly mode is achieved. Through the centripetal movement of the three claws of the pneumatic chuck, the three-point clamping deformation of the thin-walled cylindrical shell is achieved, the mechanical limit and assembly between the internal components of the shell is completed. And the kinematic and dynamic simulation analysis of the internal transmission mechanism of the pneumatic system is completed through simulation software.

In the actual process of the embedded software development, there are various problems such as incomplete configuration items, frequent changes and version iterations. Configuration management provides resolving method for these questions. A method to practical risks and analyzing corresponding control measures is proposed to promote the resolution of integrity and consistency of products.