Efficiency of cw HF lasers with resonant optical pumping

Numerical studies are made of the amplifying and lasing characteristics of cw HF lasers with resonant optical pumping for various threshold gains g_th and molar concentrations α_HF of HF molecules. It is found that the dependence of the quantum efficiency η_q of these lasers on α_HF is nonmonotonic and the maximum of η_q corresponds to α_HF = 0.002. A comparison is made between the calculated and experimental laser characteristics. A new interpretation is given of the experimentally observed changes in the lasing spectrum with varying α_HF.