Single shot measurement of the photonic band structure in a Floquet-Bloch lattice realised with coupled fiber rings

TL;DR

This paper demonstrates a novel single-shot optical method to directly measure the Floquet-Bloch band structure in a photonic lattice created with coupled fiber rings, enabling detailed analysis of topological effects.

Contribution

The authors introduce a new experimental technique for directly measuring Floquet-Bloch bands in photonic systems using a time-multiplexed fiber ring lattice.

Findings

Successful measurement of Floquet-Bloch bands via Fourier transform of impulse response

Accurate characterization of lattice eigenmodes across the Brillouin zone

Potential to observe topological effects in linear and nonlinear Floquet systems

Abstract

Floquet-Bloch lattices are systems in which wave packets are subjet to periodic modulations both in time and space, showing rich dynamics. While this type of lattices is difficult to implement in solid-state physics, optical systems have provided excellent platforms to probe their physics: among other effects, they have revealed genuine phenomena such as the anomalous Floquet topological insulator and the funnelling of light into localised interface modes. Despite the crucial importance of the band dispersion in the photon dynamics and the topological properties of the lattice, the direct experimental measurement of the Floquet-Bloch bands has remained elusive. Here we report the direct measurement of the Floquet-Bloch bands of a photonic lattice with a single shot method. We use a system of two coupled fibre rings that implements a time-multiplexed Floquet-Bloch lattice. By Fourier transforming the impulse response of the lattice we obtain the band structure together with an accurate characterization of the lattice eigenmodes, i. e. the amplitudes and the phases of the Floquet-Bloch eigenvectors over the entire Brillouin zone. Our results open promising perspectives for the observation of topological effects in the linear and nonlinear regime in Floquet systems.