Four-wave mixing on thermal nonlinearity with feedback for signal or object waves

The coincidence of the amplitude reflection coefficients, half-widths of the spatial frequencies bands of a four-wave radiation converter on thermal nonlinearity with feedback for signal or object waves has been shown at equal pump waves intensity. The dependence of the amplitude reflection coefficient, spatial selectivity of the four-wave radiation converter on thermal nonlinearity on the pump waves intensity has been analyzed. An increase in the half-width of the spatial frequency band is observed with an increase in the pump waves intensity at the compensation for the phase shift arising as a result of the propagation of the pump waves in the medium. There is a threshold value of the pump waves intensity, above which the value of the amplitude reflection coefficient of the four-wave converter with feedback for signal or object waves, is less than in the absence of feedback.