Gain and saturation parameter of a waveguide laser with distributed losses

An analysis is made of the problem of allowance for distributed losses α_d in a gas-discharge waveguide laser when a determination is made of the gain g₀ and of the saturation parameter I_s from the output power P. Comparisons are made of the values of g₀ and I_s for a carbon monoxide waveguide laser, found experimentally by the method of calibrated losses allowing for and ignoring α_d. A description is given of the method for the determination of g₀ of a waveguide laser by a probe laser (which eliminates the influence of α_d) and the results are given for the 1846.9 cm^–1 line of the CO molecule. It is shown that when g₀ and I_s are calculated from the measured values of P, an allowance must be made for α_d because otherwise the results are overestimated. Measurements are reported of the values of P obtained for CO waveguide lasers with capillaries of different lengths and a comparison is made between the experimental data and those calculated allowing for the values of α_d.