Manipulation for one-way large-area helical waveguide states in topological heterostructure

Abstract

Photonic topological insulators (PTIs) have been extensively attracting attention recently because of unique characteristics in manipulating electromagnetic waves. In this work, we construct a kind of heterostructure consisting of a domain of nontrivial topological photonic crystals (TPCs) sandwiched between two domains of trivial TPCs by using all-dielectric materials, systematically analyze and discuss projected photonic bulk bands structures with 3, 5, 6 layers nontrivial TPCs in heterostructures, and theoretically achieve one-way large-area helical topological waveguide states with pseudospin-polarized and robustness. Based on intrinsic chirality of helical edge states, we calculate the chirality map of one-way large-area topological waveguide states by quantifying Stokes parameters. Furthermore, we realize a series of specific manipulation for one-way large-area topological waveguide states, for example, we achieve interesting waveguide functionalities with valley-splitting and four-channel of one-way large-area topological waveguide states in a topological heterostructure with a cross-like route based on chirality map. We realize a wavelength division multiplexing in specific topological heterostructure based on distributions of dispersion curves of topological waveguide states in different heterostructures. The work provide a new promising and valid guideline for practical design and applications in multi-function integrated photonic devices, such as high-capacity energy transport, field enhancement.