Tunable multi-channel circulator based on valley topological photonic crystals

In this paper, we present a magnet-free six-port optical circulator based on two-dimensional valley topological photonic crystals with engineered line defects in chiral unit cells. This design enables topologically protected unidirectional transmission and on-demand channel reconfiguration. Numerical simulations demonstrate operation in the 195.37–196.37[Formula: see text]THz (1534–1527[Formula: see text]nm) with insertion loss [Formula: see text]0.9[Formula: see text]dB and isolation [Formula: see text]35[Formula: see text]dB, maintained consistently across both basic and reconfigured structures. This approach provides a pathway toward highly integrated, reconfigurable photonic devices.