Constructing three-dimensional photonic topological insulator using two-dimensional ring resonator lattice with a synthetic frequency dimension

TL;DR

This paper demonstrates that a 2D array of ring resonators can function as a 3D topological insulator by incorporating a synthetic frequency dimension, enabling robust photon transport and potential novel photonic devices.

Contribution

It introduces a method to realize three-dimensional topological insulators using a 2D resonator lattice with a synthetic frequency dimension, simplifying previous complex geometries.

Findings

A 2D ring resonator array exhibits 3D topological insulator behavior when including the frequency dimension.

Modulating resonators creates a screw dislocation, enabling robust photon transport along the frequency axis.

The approach allows exploration of 3D topological physics in standard integrated photonics platforms.

Abstract

In the development of topological photonics, achieving three dimensional topological insulators is of significant interest since it enables the exploration of new topological physics with photons, and promises novel photonic devices that are robust against disorders in three dimensions. Previous theoretical proposals towards three dimensional topological insulators utilize complex geometries that are challenging to implement. Here, based on the concept of synthetic dimension, we show that a two-dimensional array of ring resonators, which was previously demonstrated to exhibit a two-dimensional topological insulator phase, in fact automatically becomes a three-dimensional topological insulator, when the frequency dimension is taken into account. Moreover, by modulating a few of the resonators, a screw dislocation along the frequency axis can be created, which provides robust transport of photons along the frequency axis. Demonstrating the physics of screw dislocation in a topological system has been a significant challenge in solid state systems. Our work indicates that the physics of three-dimensional topological insulator can be explored in standard integrated photonics platforms, leading to opportunities for novel devices that control the frequency of light.