Six-wave interaction with double wave front reversal on thermal nonlinearity in a medium with a nonlinear absorption coefficient

The spatial selectivity of a six-wave radiation converter w1 + w1 + w2 - w1 - w1 = w2 on thermal nonlinearity with allowance for the nonlinear absorption coefficient was studied. Relationships for the half-bandwidths of the spatial frequencies of object waves that are related both directly to the thermal nonlinearity and to the nonlinear character of variation of the absorption coefficient with varying signal wave divergence, nonlinear medium thickness, and pump wave intensity were analyzed. It was shown that for a highly diverging signal wave, the half-bandwidths of the spatial frequencies of object waves with a double-reversed wavefront are several times different.