Study of the first Stokes lines of Raman cell full of CH_4, H_2, D_2 and their mixture with Ar, He gases

摘要

Raman frequency shifter is a useful method extending laser wavelength, the first Stokes of CH_4, H_2, and D_2 pumped by the fourth harmonic of Nd:YAG laser can be used in DIAL measurement of the trace gases. The stability and energy of SRS are related to focal length of lens, active gas pressure, input energy, buffer gas elements and pressure. We detect the stability and energy of the first Stokes line under pure active and mixture with Ar or He. From our experiment, the stability of pure CH_4, H_2 are almost same under different pressure, however the stability of pure D_2 changes with pressure. The energy conversion efficiency on S1 is different among pure gas (CH_4, H_2, D_2). Furthermore, the optimal output energy of the first Stokes line of CH_4, H_2, D_2 are got independently at moderate active gas pressure mixing with moderate buffer pressure.