Tunable light flow control in valley photonic crystal waveguide

TL;DR

This paper demonstrates tunable control of light flow in a valley photonic crystal waveguide through phase manipulation, enabling dynamic routing and dispersion control of topological edge states for advanced photonic applications.

Contribution

It introduces a method for continuously tuning light flow and topological edge state dispersion in valley photonic systems using phase control of microwave antennas.

Findings

Light flow splitting ratio can be tuned from 0.9 to 0.1.

Topological edge states are observed at photonic domain walls.

Tunable edge state dispersion from gapless to gapped bands.

Abstract

The exploration of binary valley degree of freedom in topological photonic systems has inspired many intriguing optical phenomena such as photonic Hall effect, robust delay lines, and perfect out-coupling refraction. In this work, we experimentally demonstrate the tunability of light flow in a valley photonic crystal waveguide. By continuously controlling the phase difference of microwave monopolar antenna array, the flow of light can split into different directions according to the charily of phase vortex, and the splitting ratio varies smoothly from 0.9 to 0.1. Topological valley transport of edge states is also observed at photonic domain wall. Tunable edge state dispersion, i.e., from gapless valley dependent modes to gapped flat bands, is found at the photonic boundary between a valley photonic crystal waveguide and a perfect electric conductor, leading to the tunable frequency bandwidth of high transmission. Our work paves a way to the controllability and dynamic modulations of light flow in topological photonic systems.