Synthetic dimensions in integrated photonics: From optical isolation to 4D quantum Hall physics

TL;DR

This paper explores the use of synthetic dimensions in integrated photonics, enabling topological phenomena like optical isolation and 4D quantum Hall effects through engineered gauge fields and mode manipulation.

Contribution

It introduces a method to utilize different modes of silicon ring resonators as an extra dimension, facilitating topological effects in photonic systems.

Findings

Demonstration of a topologically-robust optical isolator in 1D resonator chains.

Proposal of a driven-dissipative analog of the 4D quantum Hall effect in 3D resonator lattices.

Use of external modulation to generate engineered gauge fields in photonic systems.

Abstract

Recent technological advances in integrated photonics have spurred on the study of topological phenomena in engineered bosonic systems. Indeed, the controllability of silicon ring-resonator arrays has opened up new perspectives for building lattices for photons with topologically nontrivial bands and integrating them into photonic devices for practical applications. Here, we push these developments even further by exploiting the different modes of a silicon ring resonator as an extra dimension for photons. Tunneling along this synthetic dimension is implemented via an external time-dependent modulation that allows for the generation of engineered gauge fields. We show how this approach can be used to generate a variety of exciting topological phenomena in integrated photonics, ranging from a topologically-robust optical isolator in a spatially one-dimensional (1D) ring-resonator chain to a driven-dissipative analog of the 4D quantum Hall effect in a spatially 3D resonator lattice. Our proposal paves the way towards the use of topological effects in the design of novel photonic lattices supporting many frequency channels and displaying higher connectivities.