Photonic gauge potential in a system with a synthetic frequency dimension

TL;DR

This paper introduces a synthetic frequency dimension in a photonic system, demonstrating how a gauge potential can be engineered to create topologically protected states for efficient frequency conversion.

Contribution

It generalizes the concept of photonic gauge potential by incorporating a synthetic frequency dimension, enabling new topological photonic phenomena.

Findings

Demonstrates gauge potential in synthetic frequency space

Creates topologically protected one-way edge states

Enhances high-efficiency generation of higher-order side bands

Abstract

We generalize the concept of photonic gauge potential in real space, by introducing an additional "synthetic" frequency dimension in addition to the real space dimensions. As an illustration we consider a one-dimensional array of ring resonators, each supporting a set of resonant modes having a frequency comb with spacing $\Omega$, undergoing a refractive index modulation at the modulation frequency equal to $\Omega$. We show that the modulation phase provides a gauge potential in the synthetic two-dimensional space with the dimensions being the frequency and the spatial axes. Such gauge potential can create a topologically protected one-way edge state in the synthetic space that is useful for high-efficiency generation of higher-order side bands.