Novel Approaches to Phase Conjugation Utilizing Ultrafast Artificial Kerr Media

Abstract

Non-linear adaptive optics presents one approach for overcoming phase distortions encountered during propagation of laser radiation. If degenerate four-wave mixing is accomplished via quantum transitions, the temporal response of the medium to phase distortions is limited only by the speed of light. This, combined with the fidelity of the signal as well as the inherent mechanical simplicity of this technique, are encouraging features which suggest that phase conjugation can be utilized in actual laser systems. Unfortunately, most non-linear media which are utilized for phase conjugation are characterized by efficiencies which are too low for practical applications. This difficulty is particularly troublesome when only weak pump fields of only a few watts per square centimeter are available. Furthermore, one would prefer to utilize non-linear media which do not have resonance conditions.