Thermo‐optical Tunable Ultracompact Chip‐Integrated 1D Photonic Topological Insulator

An on‐chip integrated one‐dimension topological insulator in the optical communication range is realized directly in an integrated photonic circuit. The system takes on a configuration of a 220 nm thick 1D photonic crystal heterostructure sandwiched between two gold films. A photonic topological edge state centered at 1550 nm is obtained for the chip‐integrated one‐dimension topological insulator made of a silicon/SiO 2 photonic crystal heterostructure with a feature size of only 2.25 µm integrated with a silicon waveguide. On/off switching of the photonic topological edge state was also achieved in a 1D topological insulator made of a VO 2 /SiO 2 photonic crystal heterostructure based on a thermally induced insulator‐to‐metal transition of VO 2 . This system not only paves the way for practical applications of photonic topological insulators in integrated photonic devices and chips but also provides a platform for fundamental studies of topological photonics.