Topological insulator based Tamm plasmon polaritons

Topological insulators as relatively new quantum materials with the topologically protected conducting Dirac surface state reveal fantastic electronic and photonic characteristics. The photonic behaviors of topological insulators are particularly significant for exploring their optical phenomena and functional devices. Here, we present the generation of Tamm plasmon polaritons (TPPs) in a topological insulator multilayer structure consisting of a Bi_1.5Sb_0.5Te_1.8Se_1.2 (BSTS) nanofilm and a one-dimensional photonic crystal (PC). The results illustrate that the TPP electric field can locally concentrate between the BSTS nanofilm and PC, contributing to the improved light-BSTS interaction with a 3-fold enhancement of light absorption. It is also found that the near-infrared TPP response can be dynamically tailored by adjusting the PC layer thickness, BSTS nanofilm thickness, and angle of incident light. The theoretical calculations are in excellent agreement with the numerical simulations. Additionally, the TPP field intensity and light-topological insulator interaction are capable of being further reinforced by introducing a dielectric spacer between the BSTS nanofilm and PC. Our results will enrich the optical characteristics and application potential of topological insulators.