THE NONLINEAR-OPTICAL PROCESSES OF OPSE, SHRS, FWPM AND THEIR COMPETITIONS

The complex nonlinear optical process induced by two-photon-resonant e xcitation of Na 3S-4D has been thoroughly studied and the generated co herent radiation in the vicinity of 2.34 mum measured and analysed. Ba sed on the observation of forward and backward output it is believed t hat the complex process is composed of the optical-pumped stimulated e mission (OPSE), stimulated hyper-Raman scattering (SHRS) and four-wave parametric mixing (FWPM). They often coexist simultaneously, each dom inating over the others under different conditions, and there are obvi ous competitions among them. By adjusting experimental conditions, suc h as the temperature of medium, frequency of input light and interacti on length, high conversion efficiency has been achieved. In this work the generated coherent IR radiation centered at 2.34 mum was tunable i n 300 cm-1, with a peak power of 100 kW, and an efficiency of 2%. 18 n ew coherent UV lines were observed for the first time.