Topological Photonics Based on Dielectric Materials

Topological propagation of electromagnetic wave immune to scatterings due to bend and defect is attracting significant interest. We have revealed recently that this amazing property can be realized in photonic crystal of conventional dielectric material by tuning lattice constant appropriately. This waives application of external magnetic field and usage of special materials inherent in previous proposals. From the spatial symmetry of photonic crystal, an effective spin degree of freedom emerges in electromagnetic modes, which makes a topological state with time-reversal symmetry possible. Novel devices are expected via integration of topological photonics and electronics.