Steering of one-way large-area waveguide modes in topological heterostructures with gyromagnetic photonic crystals

Abstract

We study the steering of one-way and large-area topological waveguide modes in heterostructures consisting of a domain of ordinary photonic crystals sandwiched between two domains of magnetic-optical photonic crystals. Taking advantage of the band and mode properties of the topological heterostructures, we first demonstrate the design of four basic steering units which can realize the functionalities of forward-guiding, T-splitting, upward turning and downward turning. We demonstrate in detailed characteristic with the high-efficiency and broad-bandwidth of these basic steering units designed. Moreover, by combining these basic steering units, we implement a series of multifunctional waveguide devices, such as one-way large-area waveguide splitters with multiple channels and different angles, a highly bended large-area waveguide with five 90° corners along the propagation path, and waveguide structures supporting waveguide-cavity interaction, delay, splitting as well as storage functionalities. Importantly, all these different functionaries could be realized in a single system platform by simply reconfiguring the underlying magnetic field distributions. Our work opens up a new venue towards designing multi-functional waveguide devices by exploiting the width degree of freedom of the large-area waveguide modes.