Experimental demonstration of coupling between cavity resonance and Tamm plasmons in photonic multilayers.

Strong coupling in photonic microstructures attracts broad attention due to its promising applications in spectral control, optical sensing, and light-matter interactions. Herein, we demonstrate the coupling effect in the photonic multilayer with a planar nanocavity on a one-dimensional (1D) photonic crystal (PC). The experiment results show that the spectral profile of the coupling effect can be effectively controlled by adjusting the thickness of the dielectric layer in the nanocavity, which is in good accordance with the calculations. The coupled-oscillator theoretical analysis reveals that the coupling response exhibits a Rabi splitting of 36 meV with a distinct anticrossing behavior, which stems from the strong coupling interaction between the nanocavity resonance and Tamm plasmons (TPs) between the metallic film and PC. The coupling strength can be effectively tuned by adjusting the thickness of the metallic film on the PC. We find that the coupling between the cavity and TP modes locates in the strong coupling regime when the metallic film thickness is less than 36 nm. This work will offer a new pathway for realizing optical coupling and spectral control in photonic microstructures.