高功率连续绿光激光器的研究进展

Research progress in high-power continuous green lasers

近年来,高功率绿光激光器的快速发展引起了国内外学者的广泛关注,已经逐步应用于工业加工、3C电子行业、医疗、军事国防等领域.本文首先对高功率绿光激光相比于近红外激光的优势和主要的应用场景进行介绍,然后对二极管泵浦全固态、半导体、碟片和窄线宽光纤倍频四种类型的高功率连续绿光激光器的国内外发展现状进行总结.其中,光纤激光器具有电光效率高、体积小、光束质量好、成本较低和散热好等特点,并且单通倍频的方案具有结构简单、易于调节安装等优势.将高功率窄线宽光纤激光器和单通倍频方案结合,是实现高功率高亮度小型化绿光激光输出的理想技术方案.然后,主要分析了当前高功率窄线宽绿光光纤激光器的关键技术、发展趋势和面临的主要挑战.最后,介绍了该类型激光器在焊接工艺中的应用,并对未来的发展进行了展望.

Recently,the rapid development of high-power green lasers has attracted considerable attention from scholars worldwide and has been gradually applied in highly reflective metal processing(such as copper),the 3C electronics industry,medical treatment,underwater laser communications,and military defense.First,this paper introduces the realization of highpower green lasers and reviews research progress achieved globally in high-power continuous green lasers.Compared with solid-state lasers and disk lasers with frequency doubling,fiber lasers have a high electro-optical efficiency,small size,good beam quality,low cost,and good heat dissipation.The single-pass frequency-doubling solution has a simple structure and is easy to adjust and install.The combination of a high-power narrow-linewidth fully polarized fiber laser and a singlepass frequency-doubling scheme is an outstanding ideal solution to achieve high-power and high-brightness miniaturized green laser output.Then,based on the theory of nonlinear effects combined with the second harmonic generation,the formula for efficient frequency doubling is derived.The theoretical and technical study of fiber laser single-pass frequency doubling has been conducted based on the scheme of noncritical phase matching LBO-crystal single-pass frequency doubling with narrow-linewidth linearly polarized fiber laser as the fundamental frequency source,which provides a feasible solution for the localization of high-power green lasers.The main research objectives of this paper are as follows:(1)The research background,application prospects,and development overview of high-power green lasers are introduced.Then,the processing advantages of high-power green lasers are identified and compared with those of near-infrared and blue lasers,and the common technical routes for generating high-power green lasers are compared.(2)Four types of highpower continuous green lasers are introduced:diode-pumped all-solid-state lasers,semiconductor lasers,disk lasers,and narrow-linewidth fiber lasers with frequency doubling.The research progress in narrow-linewidth fully polarized fiber lasers is presented to summarize their current global development status,and the common frequency-doubling crystals and structures and their respective advantageous features are analyzed.The narrow-linewidth linearly polarized fiber laser combined with the LBO-crystal single-pass frequency-doubling solution has the advantages of low cost and simple structures.Thus,this solution is analyzed to provide a feasible solution for generating kilowatt-class high-power green lasers.(3)The key technologies,development trends,and main challenges of the current high-power narrow-linewidth green fiber lasers are presented.The research progress in high-power narrow-linewidth linearly polarized fiber lasers is discussed,and the technologies of narrow-linewidth seed lasers,such as seed source of fiber oscillators and singlefrequency phase modulation,laser power amplification,nonlinear effect suppression,high-efficiency frequency doubling,are investigated in depth.The advantages of fiber oscillator lasers and single-frequency phase modulation seed sources in narrow linewidth and the suppression of nonlinear effects are analyzed.The theoretical study of LBO based on phase matching for an efficient frequency multiplication output is presented according to the Sellmeier equation of crystals.(4)The application of high-power green lasers in the welding processes of metals,such as copper and aluminum alloys,is studied.Finally,an outlook on the development of high-power green laser technology is provided.In the future,more research should be devoted to the study of high-power narrow-linewidth linearly polarized green lasers.