Design of Waveguide Beam Splitter Based on Topological Photonic Crystals With Square Lattice

Recently, topological photonic crystals have been widely investigated due to their unique properties of controlling light propagation. In the present work, a kind of square lattice photonic crystals composed of regular octagonal dielectric columns is proposed, which realizes topological phase transitions by inverting the material of the dielectric column without breaking the symmetry of C4. The topological edge states with different Zak phases are studied by constructing the combined structures of different photonic crystals. The robustness of topological edge states is verified, and a waveguide beam splitting system based on topological photonic crystals is designed to realize the beam splitting function of specific wavelength. It opens up a new way for the development of new optical communication devices.