Coherent properties of optical phase conjugation in disordered media

J. P. Lavoine, A. A. Villaeys

Amnon Yariv, Mark Cronin‐Golomb

Vladimir I. Yudson, P. Reineker

Recently it was shown that in disordered media, nonlinear backscattering of phase-conjugated signal light is possible in the presence of only a single pump wave, in contrast to the case of an ordered medium where two counterpropagating pump waves are necessary. Formally, this disorder-induced nonlinear process corresponds to the cooperon-channel (back)scattering of the signal wave in the presence of diffusion propagation of the pump wave. (The cooperon is the Cooper particle-particle diffusion propagator.) In this contribution, the question is considered whether the disorder-induced backscattering of phase-conjugated light can restore the disturbed signal wave front as it does in the ordered case. Examining correlations of the outgoing waves corresponding to different incoming signal waves, it is shown that the backscattered waves possess a ``phase memory'' even for a large difference of the angles of incidence of incoming waves. This is in contrast to the case of linear backscattering, where such correlations take place only at a very small difference of the angles of incidence (of the order of backscattering peak width). Thus the phase conjugation in disordered media does possess the peculiar coherent properties of that in ordered media.

V. E. Kravtsov, Vladimir I. Yudson, V. M. Agranovich

V. E. Kravtsov, Vladimir I. Yudson, V. M. Agranovich

In the case of disordered nonlinear media, it is shown that in four-wave mixing a phenomena analogous to phase conjugation may occur. In contrast to the case of transparent media in which two counterpropagating pump waves (with frequency ${\ensuremath{\omega}}_{p}$) are required, phase conjugation may occur in the presence of a single pump wave injected into the disordered nonlinear material. We find that in the angular distribution of radiation of frequency ${\ensuremath{\omega}}_{s}$ (${\ensuremath{\omega}}_{s}$=2${\ensuremath{\omega}}_{p}$-${\ensuremath{\omega}}_{i}$, where ${\ensuremath{\omega}}_{i}$ is the frequency of probe wave) there is a narrow peak in the backscattered direction associated with the probe wave. The intensity of this peak may be some orders of magnitude larger than the diffuse background at the frequency ${\ensuremath{\omega}}_{s}$.

Chr. Flytzanis, Govind Prasad Agrawal, Carson L. Tang