汞蒸汽中利用四波和频产生125nm附近可调谐真空紫外激光

GENERATION OF TUNABLE VUV LASER NEAR 125nm BY FOUR WAVE SUM MIXING IN Hg VAPOR

以氩为匹配气体的汞蒸汽四波和频实验中,一束泵浦光(ω_1)与汞原子6~1S_0—7~1S_0严格双光子共振,当另一束泵浦光(ω_3)在汞原子7~1S_0—9~1P_1跃迁的蓝端调频时,产生可调谐的真空紫外(VUV)激光(ω_4=2ω_1+ω_3),其波长可调谐范围为 124.80—125.06nm。用小信号近似下的四波和频理论对实验结果进行分析。特别着重讨论了影响最佳相位匹配的因素和在弱泵浦光条件下增大调谐范围的途径。

Tunable VUV laser (ω4 = 2ω1 + ω3) in the range of 124.80-125.06nm is gene-rated by four-wave sum mixing in Hg vapor with Ar as buffer gas, when one of the pump beams (ω1) is tuned exactly to 6~1S_0-7~1S0 two-photon resonance and another pump beam (ω3) on the blue side of 7~1S_0-9~1P1 transition. The experimental results are analysed with the small signal four-wave sum mixing theory. The factors affecting the best phase matching condition and the methods to expand the tunable range of VUV output in the weak pump case are discussed.