Coupling of photonic topological states and their dynamical control based on liquid crystal.

Optical field manipulation inspired by topology theory has recently drawn great research attention in nanophotonic. For flexible and programmable light management, the capacity to dynamically regulate the photonic topological states in fixed optical artificial microstructures is essential. Here, we propose a dynamic light manipulation of a two-dimensional (2D) photonic lattice aided by liquid crystals, which is composed of all-dielectric photonic crystals with distinct topological phases. In brief, by submerging the well-designed photonic lattice into a liquid crystal (LC), the topological edge and corner states can be actively modulated by applying external bias voltage, which offers an electrically switchable tuning capability, enabling the coupling between higher-order topological states in a structurally deterministic photonic structure. As a proof-of-principle, we use the 1D topological edge states and 0D topological corner states in one sample, respectively, to mimic line-waveguides and corner-cavities, and demonstrate their selective couplings with Fano-like profile driven by electric bias. Our work offers an effective and flexible way for light control in the potential active topological photonic devices.