Phonon-induced anomalous gauge potential for photonic isolation in frequency space

TL;DR

This paper demonstrates phonon-induced anomalous gauge potentials in frequency space, enabling nonreciprocal light propagation and switching in integrated photonic devices through coherent phase control and Aharonov-Bohm interferometry.

Contribution

It introduces a novel phonon-induced gauge potential with non-inverted phases in frequency space, enabling new nonreciprocal photonic functionalities.

Findings

Realization of phonon-induced anomalous gauge potentials in frequency domain

Implementation of frequency-domain photonic isolators with controllable directionality

Demonstration of coherent unidirectional frequency conversion

Abstract

Photonic gauge potentials are crucial for manipulating charge-neutral photons like their counterpart electrons in the electromagnetic field, allowing analogous Aharonov-Bohm effect in photonics and paving the way for critical applications like photonic isolation. Normally, a gauge potential exhibits phase inversion along two opposite propagation paths. Here we experimentally demonstrate phonon-induced anomalous gauge potentials with non-inverted gauge phases in a spatial-frequency space, where quasi-phase-matched nonlinear Brillouin scatterings enable such unique direction-dependent gauge phases. Based on this scheme, we construct photonic isolators in the frequency domain permitting nonreciprocal propagation of light along the frequency axis, where coherent phase control in the photonic isolator allows switching completely the directionality through an Aharonov-Bohm interferometer. Moreover, similar coherent controlled unidirectional frequency conversions are also illustrated. These results may offer a unique platform for a compact, integrated solution to implement synthetic-dimension devices for on-chip optical signal processing.