The 2 μm wavelength belongs to the eye-safe band and has a wide range of applications in the fields of lidar, biomedicine, and materials processing. With the rapid development of military, wind power, sensing, and other industries, new requirements for 2 μm solid-state laser light sources have emerged, especially in the field of lidar. This paper focuses on the research progress of 2 μm solid-state lasers for lidar over the past decade. The technology and performance of 2 μm pulsed single longitudinal mode solid-state lasers, 2 μm seed solid-state lasers, and 2 μm high power solid-state lasers are, respectively, summarized and analyzed. This paper also introduces the properties of gain media commonly used in the 2 μm band, the construction method of new bonded crystals, and the fabrication method of saturable absorbers. Finally, the future prospects of 2 μm solid-state lasers for lidar are presented.

Due to its exceptional advantages, such as high specific strength, high specific modulus, and good fatigue resistance, carbon-fiber-reinforced plastic (CFRP) is frequently utilized in aerospace, aviation, automotive, rail transportation, and other areas. Composite components typically need to be joined and integrated. In the equipment manufacturing industry, the most used methods for processing composite components are cutting, drilling, and surface treatment. The quality of CFRP is significantly impacted by traditional mechanical processing, causing flaws like delamination, burrs, and tears. Laser processing technology has emerged as a crucial method for processing CFRP for its high quality, non-contact, simple control, and automation features. The most recent research on the laser processing of CFRP is presented in this paper, supporting scientists and engineers who work in the field in using this unconventional manufacturing technique. This paper gives a general overview of the key features of laser processing technology and the numerous machining techniques available. The concepts and benefits of laser processing technology are discussed in terms of the material properties, mode of operation, and laser characteristics, as well as the methods to achieve high efficiency, low damage, and high precision. This paper reviews the research development of laser processing of carbon-fiber-reinforced plastics, and a summary of the factors affecting the quality of CFRP laser processing. Therefore, the research content of this article can be used as a theoretical basis for reducing thermal damage and improving the processing quality of laser-processed composite materials, while, on this basis, we analyze the development trend of CFRP laser processing technology.

The application of laser fabrication of fiber-reinforced polymer (FRP) has an irreplaceable advantage. However, the effect of the plasma generated in laser fabrication on the damage process is rarely mentioned. In order to further study the law and mechanism of laser processing, the laser process was measured. CFRP and GFRP materials were damaged by a 1064 nm millisecond pulsed laser. Moreover, the propagation velocity and breakdown time of plasma plume were compared. The results show that GFRP is more vulnerable to breakdown than CFRP under the same conditions. In addition, the variation of plasma plume and material surface temperature with the number of pulses was also studied. The results show that the variation trend is correlated, that is, the singularities occur at the second pulse. Based on the analysis of experimental phenomena, this paper provides guidance for plasma phenomena in laser processing of composite materials.

Since the discovery of the frequency doubling phenomenon in the 1960s, there has been a continuous emergence of solid-state lasers with varying wavelengths. Technological advancements have facilitated the generation of various types of ultraviolet lasers by employing diverse frequency doubling crystals and pump sources. Ultraviolet lasers find widespread applications in processing, microelectronics, grating fabrication, and beyond. This article presents a comparative analysis of the strengths and weaknesses of different ultraviolet lasers, explores solid-state ultraviolet lasers of varying wavelengths achieved through frequency doubling, and delineates their diverse applications.

Carbon fiber-reinforced polymer (CFRP), known for its light weight, high strength, and corrosion-resistant properties, is extensively used in the lightweight design of satellite components, the optimization of electronic device casings, and the processing of high-performance composite materials in the defense sector. This study employs picosecond laser drilling technology for the precision machining of CFRP, demonstrating its advantages over traditional mechanical drilling and other unconventional methods in significantly reducing the heat-affected zone (HAZ) and enhancing hole wall quality. The optimization of laser power, scanning speed, and fill times via response surface methodology (RSM) significantly reduced the hole wall taper to 4.160° and confined the HAZ to within 18.577 μm, thereby enhancing machining precision. The actual test results show that the deviations in the hole taper and HAZ width were 5.0% and 2.2%, respectively, further verifying the effectiveness of the optimization method. This technique not only improves processing quality but also offers significant industrial application value in the machining of materials for related high-tech fields.