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采用单纵模Nd:YAG二倍频激光泵浦,研究了CH4气体中的受激喇曼散射．实验发现,当激光的重复频率为2 Hz,1．1 MPa CH4中,泵浦能量为95 mJ时,后向一级斯托克斯(BS1)的量子转化效率可达73％,并且由于激光脉冲的张弛振荡,BS1的脉宽被压窄到1．2 ns,峰值功率达到了泵浦光功率的2．7倍,其光束质量大大优于泵浦光．在同样条件下,而重复频率为10 Hz时,BS1的量子转化效率降低为36％,但对光束质量影响不大,这是因为BS1呈现为与泵浦光波前翻转的复制光波,可以补偿热畸变．研究结果表明,如果设计一个CH4／He混合气体的带封闭循环冷却系统的高性能630 nm喇曼激光器,可能有其实际应用价值．
The stimulated Raman scattering in CH4 gas was studied by using a single longitudinal mode Nd: YAG double frequency laser pump. The experimental results show that when the laser repetition frequency is 2 Hz and the pump energy is 95 mJ in 1.1 MPa CH4, the quantum efficiency of the backward primary Stokes (BS1) can reach 73% The relaxation of the pulse, the BS1 pulse width is narrowed to 1.2 ns, the peak power reaches 2.7 times the pump power, the beam quality is much better than the pump light. Under the same conditions, when the repetition frequency is 10 Hz, the quantum conversion efficiency of BS1 is reduced to 36%, but it has little effect on the beam quality. This is because BS1 appears as a replicated light wave that is inverted with the pump wavefront and compensates for the heat distortion. The results show that if the design of a CH4 / He mixed gas closed loop cooling system with high performance 630 nm Raman laser may have practical value.