Stark-induced three-wave mixing in molecular gases - Part II: Experiment

The first observation of resonantly enhanced, dc-induced, three-wave mixing in a gas is presented. A CW CO
2
laser beam and microwave radiation at 4 GHz are mixed in a microwave Stark cell containing gaseous NH
2
D. A single new sideband, 4 GHz below the applied CO
2
laser frequency, is observed with the aid of a scanning Fabry-Perot interferometer. The dependence of the sideband signal on gas pressure, microwave frequency, applied dc field, and microwave power are presented and compared with theoretical predictions.