On the role of thermal nonlinearity in degenerate interactions in saturated laser media

The production of the temperature grating of the refractive-index variation upon recording a gain grating in solid laser media is considered. The dependence between the amplitudes of the temperature grating and saturated-gain grating is found. Based on the dependence obtained, the phase component of the inverse-population grating in a Nd:YAlO₃ crystal is determined.