title: Photonic gauge potential in a system with a synthetic frequency dimension.
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 Ω, and undergoing a refractive index modulation at the modulation frequency equal to Ω. 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 a 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.
authors.forename: Luqi
authors.initials: L
authors.lastname: Yuan
authors.forename: Yu
authors.initials: Y
authors.lastname: Shi
authors.forename: Shanhui
authors.initials: S
authors.lastname: Fan