Nonlinearity-induced reciprocity breaking in a single non-magnetic Taiji resonator

TL;DR

This paper demonstrates a non-magnetic, nonlinear Taiji resonator exhibiting non-reciprocal light transmission and bistability, achieved through intensity-dependent refractive index and broken symmetry, with potential applications in integrated photonics.

Contribution

It introduces a novel nonlinear Taiji resonator that achieves non-reciprocity without magnetic materials, supported by experimental, numerical, and analytical analysis.

Findings

Non-reciprocal transmission observed experimentally.

Direction-dependent optical bistability demonstrated.

Theoretical models accurately reproduce experimental results.

Abstract

We report on the demonstration of an effective, nonlinearity-induced non-reciprocal behavior in a single non-magnetic multi-mode Taiji resonator. Non-reciprocity is achieved by a combination of an intensity-dependent refractive index and of a broken spatial reflection symmetry. Continuous wave power dependent transmission experiments show non-reciprocity and a direction-dependent optical bistability loop. These can be explained in terms of the unidirectional mode coupling that causes an asymmetric power enhancement in the resonator. The observations are quantitatively reproduced by a numerical finite-element theory and physically explained by an analytical coupled-mode theory. This nonlinear Taiji resonator has the potential of being the building block of large arrays where to study topological and/or non-Hermitian physics. This represents an important step towards the miniaturization of nonreciprocal elements for photonic integrated networks.