Investigation of submillimeter-wave amplification in optically pumped molecular gases

The results are presented of measurements of the gain for certain emission lines of cw optically pumped submillimeter lasers utilizing HCOOH, CH₃OH, C₂H₂F₂, CH₃I, and CD₃I molecules. The gain was measured as a function of the intensity of the pump radiation, gas pressure, and polarization of the input signal. The degree of polarization anisotropy of the excited medium depended on the type of pumping transition. The largest gain, 3.15 dB/m, was obtained for the λ = 432.6μ transition in the HCOOH molecule.