Topological light guiding and trapping via shifted photonic crystal interfaces

Abstract

The exploration of topological states in photonic crystals has inspired a number of intriguing discoveries, which in turn provide new mechanisms for the manipulation of light in unprecedented ways. Here, we show that light can be effectively guided and trapped at the shifted photonic crystal interfaces (SPCIs). The projected bandgap of SPCIs, which depends on the shift parameter, is characterized by a Dirac mass. Interestingly, the SPCI with zero Dirac mass is a glide-symmetric waveguide featured with gapless interface states that exhibit excellent transmission performance even in the presence of disorders and sharp corners. Moreover, placing two SPCIs with opposite Dirac mass together results in a photonic bound state due to the Jackiw–Rebbi theory. Our work provides an alternative way toward the design of ultracompact photonic devices such as robust waveguides and cavities as well as the cavity-waveguide coupled systems that can serve as high-performance building blocks of miniature integrated topological photonic circuits.