Photo-Reconfigurable Supercoupling Induced Transparency in On-Chip Topological Edge State Cavities.

Electromagnetically induced transparency is a quantum interference effect that eliminates optical absorption in an opaque medium. The resulting narrow transparency window, accompanied by a pronounced slow-light effect, has enabled extensive applications in light storage, quantum information processing, and nonlinear optics. Recently, topological photonic systems have emerged as a powerful platform for robust on-chip light manipulation with topological protection. Here, we demonstrate a form of induced transparency enabled by the supercoupling between a leaky and a guided topological edge state cavity (TESC). The local valley vortices facilitate coupling between TESCs even across a distance of 4.3 wavelengths and induce a transparency window with negligible reflection due to the valley-locked momentum. When the supercoupled TESCs system operates in the strong-driving regime, frequency detuning of TESCs leads to strong mode splitting and a clear avoided crossing. Using an optical pump to photoexcite the all-silicon TESCs in the weak-driving regime, we achieve photo-reconfigurable supercoupling induced transparency (SIT), allowing dynamic control of group delay while maintaining constant transmittance. SIT opens new possibilities for manipulating light flow and controlling slow-light effects, offering promising applications in on-chip optical and quantum information processing.