Generation of UV laser by Raman shifters in D_2 and D_2/He pumped by the fourth harmonic Nd: YAG laser for SO_2 measurements

摘要

The fourth harmonic (266nm) of a pulsed Nd: YAG laser is used to pump Raman cells filled with D_2 and D_2/He. The dependences of the energy conversion efficiency of stimulated Raman scattering radiations upon the system parameters, such as the pump energy, pressure of pure D_2, and partial pressure of He in D_2/He mixture, were experimentally studied. The maximum energy conversion efficiency of the first Stokes radiation (S_1, 289.04nm) reaches 22.1% in D_2/He. The conditions to improve the energy conversion efficiency of S_1 were found. The results have been used to optimize the laser transmitter system for a SO_2 differential absorption lidar (SO_2-DIAL).