Nonlinear effects in periodic and disordered wave media.

Abstract

While there has been considerable theoretical and experimental research with quantum and classical wave propagation in linear systems, involving effects of Anderson localization, etc., there has been considerably less research with nonlinear media. A fundamental question is whether or not nonlinear effects destroy Anderson localization. There are about eight theoretical papers that treat this question, and half predict that localization is destroyed, and half predict that it is not. An experiment involving nonlinear acoustic wave propagation in a disordered potential field has been performed, and an unambiguous result has been obtained. Also, measurements of nonlinear wave propagation in a periodic field have been made, and in addition to the expected effects of canting and hysteresis, other novel effects are observed. [Work supported by NSF DMR 9000549 and ONR.]