Non-reciprocity and zero reflection in nonlinear cavities with tailored loss

TL;DR

This paper shows how to engineer losses in nonlinear optical cavities to achieve zero reflection and non-reciprocal transmission, providing analytical and numerical insights for designing optical isolators.

Contribution

It derives analytical conditions for zero-reflection in nonlinear cavities and demonstrates how coupled cavities relax these conditions, enabling tunable non-reciprocal optical devices.

Findings

Zero-reflection channels depend on driving frequency and loss rates.

Coupled cavities allow zero-reflection tuning via output leakage rate.

Numerical simulations guide the design of nonlinear optical isolators.

Abstract

We demonstrate how to tailor the losses of nonlinear cavities in order to suppress their reflection and enhance their non-reciprocal transmission. We derive analytical expressions predicting the existence of zero-reflection channels in single and coupled nonlinear cavities, depending on the driving frequency and loss rates. While suppressing the reflection from a single cavity imposes a stringent condition on the input-output leakage rates, we demonstrate that this condition can be significantly relaxed in systems of coupled cavities. In particular, zero-reflection and non-reciprocity can be achieved across a range of driving frequencies in coupled cavities by tuning the output leakage rate alone. Numerical calculations based on the driven-dissipative Gross-Pitaevksii equation, usually employed to describe microcavity polaritons, reveal the spatial phenomenology associated with zero-reflection states and provide design guidelines for the construction of nonlinear optical isolators.