Some possibilities of controlling the phase of an optical signal by wavefront reversal and parametric mixing of light waves

It is shown that wavefront reversal in combination with parametric mixing of light waves provides new opportunities for multiplication and division of the phase of an optical signal in the absence of a reference wave. The characteristic features of signal multiplication by wavefront reversal are considered for the case of partial spatial coherence of the initial radiation. In particular, it is found how the relative fraction of a plane component of second-harmonic radiation depends on the parameters which characterize the degree of spatial coherence of optical radiation.