Reconfigurable synthetic dimension frequency lattices in an integrated lithium niobate ring cavity

Abstract

Harnessing non-spatial properties of photons as if they represent an additional independent coordinate underpins the emerging synthetic dimension approach. It enables probing of higher-dimensional physical models within low-dimensional devices, such as on a planar chip where this method is relatively nascent. We demonstrate an integrated thin-film lithium niobate ring resonator that, under dynamic modulation, simulates a tight-binding model with its discrete frequency modes representing lattice sites. Inter-mode coupling, and the simulated lattice geometry, can be reconfigured by controlling the modulating signals. Up to a quasi-3D lattice connectivity with controllable gauge potentials has been achieved by simultaneous synchronized nearest-, second- and third-nearest-neighbor coupling, and verified by acquiring synthetic band structures. Development of synthetic frequency dimension devices in the thin-film lithium niobate photonic integration platform is a key step in increasing the complexity of topological models achievable on a chip, combining efficient electro-optic mode coupling with non-linear effects for long-range mode interactions. Lithium niobate on insulator (LNOI) is emerging as a powerful photonic integration platform for synthetic dimension approaches that enable probing of higher-dimensional physical models within low-dimensional devices. The authors present a LNOI ring device, whose frequency modes represent lattice sites for versatile simulation of tight-binding models with up to three-dimensional connectivity.