Nonlinearity-Induced Reciprocity Breaking in a Single Nonmagnetic Taiji Resonator

We report on the demonstration of an effective, nonlinearity-induced nonreciprocal behavior in a single nonmagnetic multi-mode Taiji resonator. Nonreciprocity is achieved by a combination of an intensity-dependent refractive index and of a broken spatial reflection symmetry. Continuous wave powerdependent transmission experiments show nonreciprocity 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 for the study of topological and/or non-Hermitian physics. This represents an important step towards the miniaturization of nonreciprocal elements for photonic integrated networks.

Automated summary

This study demonstrates an effective nonlinearity-induced nonreciprocal behavior in a single nonmagnetic multi-mode Taiji resonator, achieved through a combination of intensity-dependent refractive index and broken spatial reflection symmetry. The observations are quantitatively reproduced by numerical methods and physically explained by analytical theory, showing the potential for miniaturization of nonreciprocal elements for photonic integrated networks.