使用脉冲激光二极管抽运的单纵模激光器作为种子源,通过两级预放大器和两级主放大器的单通放大,得到重复频率400 Hz,单脉冲能量36.5 mJ,脉宽24 ns的单纵模激光输出,且输出光束质量为M2x=1.78,M2y=2.13。应用大口径锥度融石英光纤作为相位共轭镜,获得了大于50%的受激布里渊散射反射率,入射激光被压缩到6 ns左右,大幅提升了脉冲峰值功率;由于相位共轭特性,反射回的激光将沿原路返回再次通过主放大器,补偿了激光晶体中的相位畸变,并再次提取晶体中的能量进行有效放大。双通后输出重复频率400 Hz,单脉冲能量101.25 mJ,脉冲宽度6 ns左右的单纵模激光,峰值功率可高达16.8 MW,光束质量因子为M2x=1.74,M2y=1.93。可见,在应用该相位共轭镜双通过后,光束质量并没有继续恶化,而是有所提升;使用平面镜双通后的光束质量因子M2≈4,从而有效证实了该光纤相位共轭镜补偿畸变的作用。 A single-longitudinal-mode laser pumped by a pulsed laser diode is used as a seed source, and a single longitudinal mode with a repetition frequency of 400 Hz, a single pulse energy of 36.5 mJ and a pulse width of 24 ns is obtained through single pass amplification of a two-stage preamplifier and a two- Laser output, and the output beam quality M2x = 1.78, M2y = 2.13. The large-diameter taper fused silica fiber is used as the phase conjugate mirror, and the stimulated Brillouin scattering reflectivity of more than 50% is obtained. The incident laser is compressed to about 6 ns, which greatly increases the peak pulse power. Due to the phase conjugation characteristics, The reflected laser beam will travel back through the main path again, compensating for the phase distortion in the laser crystal and again extracting the energy in the crystal for efficient amplification. After double pass, single-longitudinal mode laser with repetition frequency of 400 Hz, single pulse energy of 101.25 mJ and pulse width of 6 ns can be output with peak power of up to 16.8 MW and beam quality factors of M2x = 1.74 and M2y = 1.93. It can be seen that the beam quality does not continue to deteriorate after application of the two-pass conjugate mirror of the phase, but rather improves. The beam quality factor M2 ≈ 4 after the use of the plane mirror double pass effectively confirms that the phase compensation of the fiber phase conjugate mirror Distortion effect.