The CW-496-micron methylfluoride laser - Review and theoretical predictions

The paper presents a rate-equation model for optically pumped submillimeter wave lasers. The model accounts for rotational relaxation, velocity cross relaxation, diffusion, and the gas excitation by two pump waves traveling in opposite directions. The derived equation indicates that a direct proportion exists between small-signal gain and the saturated double-pass pump absorption coefficient. The small-signal gain is also proportional to the square of the ratio of wavelength and the pump saturation parameter in methylfluoride. It is found that when the waveguide diameter is decreased, output power increases substantially. Cavities with smaller waveguide diameters have higher waveguide propagation losses and higher mode-coupling losses. Smaller waveguide diameters also show decreased pumping efficiencies.