Four-wave interaction in a multimode waveguide with a Kerr nonlinearity in a circuit with codirectional pumping waves

The quality of image transformation in a four-wave interaction on the Kerr nonlinearity in a multimode waveguide in a circuit with codirectional pumping waves using the method of the point spread function, is analyzed. It is shown that the paraxial waveguide modes completely determine the shape of the point spread function. Increasing the angle between the pump waves leads to the appearance of a “fine” structure of the point spread function. The period of this structure decreases with increasing angle between the pump waves.