355 nm Nd:YAG激光在H2中的高效一级斯托克斯转换

对脉冲Nd:YAG激光(355 nm)在H2和H2:He-Ar混合气体中的受激拉曼散射(SRS)进行了研究.在0.5 MPa的氢气中,同时测量到从二级反斯托克斯到三级斯托克斯的多波长输出,其总转化效率达88%;而高压下只剩下一级和二级斯托克斯输出,其中二级斯托克斯最大能量转化效率达44%(对应量子效率为63%).由于高级斯托克斯的竞争,纯氢气中一级斯托克斯的最大能量转换效率不超过43%.通过向3 MPa氢气中掺入2 MPaAr气后,很好地抑制了二级斯托克斯的产生,从而获得了能量转换效率高达71%(对应量子效率为83%)的一级斯托克斯输出.对四波混频和级联受激拉曼散射在氢气多级斯托克斯产生中的作用以及惰性气体对它们的影响进行了讨论.

High-Efficiency First-Order Stokes Conversion in H2 Pumped by a Nd:YAG Laser at 355 nm

Stimulated Raman scattering (SRS) in H2 and H2:He-Ar mixture gases pumped by a pulsed Nd:YAG laser at 355 nm was investigated. Under 0.5 MPa H2, multi-wavelength output was simultaneously measured from the second-order anti-Stokes to the third-order Stokes, with a total conversion efficiency of 88%, while only the first- and the second-order Stokes output were obtained under high pressures, with a maximum energy conversion efficiency for the second-order Stokes as high as 44% (i.e., quantum efficiency of 63%). Due to the competitive suppression by high-order Stokes, the energy conversion efficiency for the first-order Stokes is no more than 43% in pure H2. By adding 2 MPa Ar into 3 MPa H2, the second-order Stokes was greatly suppressed and the first-order Stokes output reached an energy conversion efficiency as high as 71% (i.e., quantum efficiency of 83%). The effect of four-wave mixing (FWM) and cascade SRS on multi-order Stokes generation and the influence of inert gas were discussed.