In order to improve the signal-to-noise ratio for laser applications underwater, agrating resonator with an intra-cavity etalon was designed to compress the spectrum of XeF blue-green laser.First, agrating resonator was used to obtain a sub-nanometer laser linewidth, and then, a further spectral compression was performed by inserting an etalon into the grating resonator.The experimental results show that a linewidth of 0.14 nm can be obtained by using a 1 200 line/mm grating, and the linewidth can be further compressed to 39 pm by inserting an etalon, with a reflectivity of 50％, in the grating resonator.The final laser pulse energy is about 65 mJ and the pulse duration is 1μs.Although the gain coefficient of the XeF (C-A) laser is low, the optical loss of the resonator can be reasonably controlled by optimizing the working parameters of the grating and the etalon, thereby a 10 pm-level laser linewidth can be realized.%为了避免阳光背景干扰, 针对XeF (C-A) 蓝绿激光水下应用需求开展了激光线宽压缩实验以提高信噪比.采用内置标准具的光栅谐振腔开展相关实验.利用光栅腔实现亚纳米级的激光线宽输出, 然后在此基础上, 通过插入标准具进行更精细的激光线宽压缩实验.利用光栅腔, 采用1 200线/mm光栅并提高光栅辐照面积可以实现0.14nm的激光线宽输出.腔内插入反射率为50％的标准具, 可以进一步将激光线宽压缩至39pm, 激光单脉冲能量约为65mJ, 脉冲宽度为1μs.实验结果表明:尽管XeF (C-A) 蓝绿激光器的增益系数较低, 但是通过优化光栅和标准具的工作参数, 对谐振腔光学损耗进行合理的控制, 激光器可以实现10pm量级的激光线宽输出.
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