Phase-conjugation quality with four-photon interaction in a parabolic waveguide

Abstract

The effect of the mode structure of the pump waves and the length of the optical waveguide on phase conjugation quality with degenerate four-photon interaction in a parabolic optical waveguide with Kerr nonlinearity is studied. It is shown that the dependence of the overlap integral on the mode numbers of the interacting waves eliminates the possibility of ideal phase conjugation in “long” optical waveguides. As the length of the waveguide increases, the point-spread function, describing the quality of phase conjugation, is broadened and approaches some limiting form, determined by the mode structure of the pump waves. In “long” waveguides, if one of the pump waves is single-mode and the other is multimode, an increase in the mode numbers of multimode pumping affects only the contrast and symmetry of the converted image of a point. If, however, both pump waves are identical and multimode, then an increase of their mode number results in narrowing of the point-spread function.