Relaxation time of phase-conjugate reflection via four-wave mixing of radiation in the active medium of a CO2 laser

The experimental relaxation time of degenerate four-wave mixing based on the nonlinearity of saturation of the active media of TEA CO₂ lasers (~0.3 μs) is shown to be an order of magnitude less than the time calculated on the basis of the existing theories. A new mechanism is proposed to account for the relaxation of such mixing in the active media of TEA CO₂ lasers. This mechanism postulates erasure of gratings, formed in the course of the fourwave mixing, of the population inversion of the active levels of a laser due to a high rate of filling of the upper level by resonant energy transfer from nitrogen molecules.