Six-wave radiation converter based on resonant nonlinearity in a parabolic waveguide

The quality of wavefront reversal during six-wave mixing in a two-dimensional waveguide with resonant nonlinearity and the refractive index varying by a parabolic law is analyzed using a point spread function method. Assuming that one of the pump waves excites the zero mode of the waveguide and the distribution of the amplitude of the other pump wave on the edge of the waveguide changes by the Gaussian law, it is shown that at a low intensity of the single-mode pump wave, reducing the width of the Gaussian pump wave either leads to an improvement of or has little effect on the quality of wavefront reversal. At a high intensity of the single-mode pump wave, reducing the width of the Gaussian pump wave deteriorates the quality of wavefront reversal. We determine the range of changes in the width of the Gaussian pump wave in which the greatest change in the amplitude of the wave with a reversed wavefront is observed. It is shown that there is a threshold value for the width of the Gaussian pump wave at which a change in the intensity of the single-mode pump wave does not affect the quality of wavefront reversal.