Strong coupling of optical interface modes in a 1D topological photonic crystal heterostructure/Ag hybrid system.

We theoretically investigate the strong coupling of a topological photonic state (TPS) and Tamm plasmon polaritons (TPPs) in a graphene embedded one-dimensional topological photonic crystal (TPC)/Ag structure in visible range. It is shown that the strong interaction of a TPS at the TPC heterointerface and TPP at the Ag surface enables a large Rabi splitting up to 96.8 meV with a dual-narrow-band perfect absorption. A spectral linewidth of the hybrid mode can be 0.3 nm with a Q factor of 1078. The numerical results also reveal that mode coupling can be either tuned by adjusting the geometric parameters or actively controlled by the incident angle, offering a remarkable polarization-independent strong light-matter interaction. The coupled mode theory is employed to explain the strong TPS-TPP coupling. The polarization-independent and controllable strong mode coupling with a dual-narrow-band perfect absorption in this simple lamellar geometry offers new possibilities for developing various on-chip optical detection, sensing, filtering, and light-emitting devices.