Topological photonics is becoming increasingly important due to its possibility to manipulate light with topological phases. Constrained by tunable material, the concept of the topological phase of light is less employed for the realization of terahertz (THz) devices. Incorporating tunable plasmonic materials with topological photonic structures can promote topological protection at the THz frequency. Here the topological phase transition in the terahertz bands is demonstrated by integrating Dirac semi‐metal with topological photonic crystal. This work proposes photonic band inversion induced frequency splitting and absorption enhancement in bulk Dirac semi‐metal (BDS) based Tamm plasmon multilayer system. The enhancement in absorption is achieved by designing a one‐dimensional topological edge state such that the combination with the Tamm plasmon state provides topological protection to the entire BDS–photonic crystal heterostructure. The proposed structure undergoes band inversion, a topological transition in the photonic band structure. These results may facilitate the realization of terahertz topological effects and contribute to the goal of topological protection in sensing applications.
Topological insulator materials have attracted greater attention in recent years due to their conducting surface state and insulating bulk state. The unique surface states in topological insulators offer potential applications in photonics and optoelectronics. Herein, topological insulators' near-infrared plasmonic behavior is utilized to demonstrate a tunable double-mode absorber that shows an electromagnetically induced transparency (EIT)-like effect. A composite structure is formed by sandwiching a photonic crystal heterostructure between topological insulator layers. The transfer matrix method is used to examine the optical response. The evolution of the modes with changes in layer thicknesses, grating period number, and propagating angle is also investigated. The study is further extended to multichannel optical absorption by making changes in the composite structure period, and the resultant absorption spectrum shows a multichannel EIT-like effect.
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