Anomalous refractive indices of the amplifying medium in a waveguide CO2 laser

The relative changes in refractive index of the amplifying medium in a waveguide CO2 laser have been measured as a function of the inlet and outlet pressures, discharge current, gas flow rate, and intracavity power using an interferometric technique. The experiments have been made for two gas mixing ratios over a wide range of the inlet pressure. Saturated phenomena of the refractive index have been observed for increasing inlet pressure. The output power and the variation in impedance of the amplifying medium have been simultaneously measured. The dependence of the refractive index on the inlet pressure in the absence of the discharge, the electron density, and the estimation of errors in measurements are discussed.