A 60-mW solid-state deep ultraviolet (DUV) laser at 193 nm with narrow linewidth is obtained with two stages of sum frequency generation in LBO crystals. The pump lasers, at 258 and 1553 nm, are derived from a homemade Yb-hybrid laser employing fourth-harmonic generation and Er-doped fiber laser, respectively. The Yb-hybrid laser, finally, is power scaling by a 2 mm × 2 mm × 30 mm Yb:YAG bulk crystal. Accompanied by the generated 220-mW DUV laser at 221 nm, the 193-nm laser delivers an average power of 60 mW with a pulse duration of 4.6 ns, a repetition rate of 6 kHz, and a linewidth of ∼640 MHz. To the best of our knowledge, this is the highest power of 193- and 221-nm laser generated by an LBO crystal ever reported as well as the narrowest linewidth of 193-nm laser by it. Remarkably, the conversion efficiency reaches 27% for 221 to 193 nm and 3% for 258 to 193 nm, which are the highest efficiency values reported to date. We demonstrate the huge potential of LBO crystals for producing hundreds of milliwatt or even watt level 193-nm laser, which also paves a brand-new way to generate other DUV laser wavelengths.

基于多纵模振荡种子源的窄线宽光纤激光器具有光路简单、结构紧凑、可靠性高、成本低等特点，在实际工程应用以及在空间受限的载荷平台上有着显著优势，是高功率光谱合成的理想子束模块。受自脉冲效应的影响，多纵模振荡种子源的时域特性较差，导致放大过程中会产生较强的光谱展宽与受激拉曼散射效应。这限制了其输出功率的进一步提升并降低了其光谱纯度。本文首先介绍了4种常见的窄线宽种子源，并重点分析了多纵模振荡种子源中自脉冲效应产生的机理及抑制方法，对优化多纵模振荡种子源和放大器的关键技术进行了详细介绍，归纳总结了近几年的技术突破与研究成果，对未来的发展方向进行了展望分析。本文研究对基于多纵模振荡种子源的窄线宽激光器的功率提升和光谱优化提供一定思路。

A whispering gallery mode resonator (WGMR) filter can narrow laser linewidth while significantly changing the output power characteristics of fiber laser system. It is found that traditional laser output power model is invalid. We report a correction model of a narrow linewidth fiber laser filtered with a WGMR to analyze its power. We believe that the loss of the laser system and the threshold gain increase caused by the WGMR filter lead to the predominate amplified spontaneous emission during the original laser period. According to that, we assume the correction coefficient is an exponential decay related to the Er-doped fiber length in the large loss situation, and we verify it experimentally. As a result, the correction model is valid for WGMR-filtered fiber laser.

通过光纤激光光谱合成技术，可以打破单个光纤激光器输出功率受非线性因素制约的限制，实现更高功率的激光输出。通过梳理光谱合成技术的发展历程并分析其现状，对其原理及优劣势进行分析，结合自身研究，设计了一款便携式3路合成系统，通过设计及优化光纤激光器的放大结构，严格把控参与合束的子束光源的质量，将1055、1070和1085 nm三路高功率窄线宽光纤激光进行合束，对合成系统中采用的双色镜进行研究，对其膜系指标进行严格的设计，对高陡度截止滤光膜的设计方法以及制备工艺进行分析，对其热损伤规律及控制技术进行研究，优化整个合成系统，最终实现合成功率9650 W的高功率激光输出，合成效率92%，光束质量M²为1.7，并对未来双色镜光谱合成进行了展望。