详细介绍了基于1014.8 nm室温光纤激光放大器的高效外腔倍频技术, 获得了大功率的507.4 nm单频激光。高效的外腔倍频是由内置正入射三硼酸锂晶体的高增益环形腔实现的, 最高可以获得3 W的输出功率, 倍频效率高达61.5%。倍频腔输入输出功率的实验测量值与理论计算结果相符合。该倍频腔针对4 W的基频光输入设计, 在最佳工作点(4W)附近倍频效率对输入功率改变不敏感。在1.5 h内, 绿光输出功率涨落的均方根值为1.7%。大功率稳定输出的507.4 nm单频激光可通过偏硼酸钡晶体倍频产生用于冷却中性汞原子所需的253.7 nm深紫外激光, 也可直接用于探测镱原子1S0态到3P2态跃迁的光谱和相关实验。

The high power single frequency laser at 507.4 nm is proposed based on the high efficient frequency doubling technology of a 1014.8 nm room-temperature fiber laser amplifier. High efficient frequency doubling is realized in a high gain ring cavity with a normal incidence lithium triborate crystal. The double frequency efficiency is up to 61.5% and the output power is up to 3 W. The experimental data and simulated results of the input-output characteristics of the frequency doubling are coincide. The double frequency efficiency is insensitive with the input power at the peak working point when the input power of infrared laser is more than 4 W. The power fluctuation in root mean square is 1.7% in 1.5 h. The high power single frequency laser at 507.4 nm can be both used to generate the 253.7 nm ultraviolet laser for laser cooling of neutral mercury atom by barium boron oxide crystal, and to detect the transition of ytterbium atom from 1S0 to 3P2 state, and related experiments.