Nonreciprocal pulse shaping and chaotic modulation with asymmetric noninstantaneous nonlinear resonators

Abstract

Electromagnetic nonlinearity, combined with symmetry breaking, can be exploited to obtain highly nonreciprocal light transmission. In previous studies on nonreciprocity, it has been generally assumed that the material's nonlinearity responds instantaneously to the applied field. Here, we consider a noninstantaneous nonlinear response and study its influence on nonreciprocity. We show that the inclusion of such delayed effects can lead to highly nontrivial nonreciprocal dynamics, which are forbidden in the instantaneous regime. Particularly, when the characteristic delay time of the nonlinearity approaches the input pulse's duration, high-contrast nonreciprocal compression and reshaping of the pulse can be achieved. In the high-power regime, we show that it is possible to generate a nonreciprocal response in a single resonator, which, for instance, is chaotic when sourced along one direction and periodically modulated when sourced from the opposing direction. Indeed, by tuning the nonlinearity's memory time we can flexibly control the system's response, enabling a wide range of nonreciprocal functionalities in compact, passive, and bias-free devices.