High tunability and sensitivity of 1D topological photonic crystal heterostructure

Abstract

A modality to high tunability and sensing performance of one-dimensional (1D) topological photonic crystal (PC) heterostructure is realized based on a new mechanism through 1D topological PC. With inserting a defect aqueous layer as a sandwich between two 1D PCs, the transmittance gradually decreases with the increasing thickness of the defect layer. When the two layers of the topological heterostructure interface are replaced by the defect layer, the tunability, all sensing capabilities have been improved and the principle of topology is preserved. A topologically protected edge state is formed at the heterostructure interface with a highly localized electric field. For glucose sensing, high sensitivity S = 603.753 nm/RIU is obtained at the low detection limit of about DL = 1.22×10^(-4) RIU with high-quality factor Q = 2.33×10^4 and a high figure of merit FOM = 8147.814 RIU^(-1). Besides, the transmittance can be maintained more than 99% at low and/or high glucose concentrations, due to the coupling topological edge mode between defect mode and topological edge state. An excellent platform is examined for the design of a topological photonic sensor which is a flexible platform that can be used for any type of sensor solely by replacing the interface layers with the sensor materials. Thus, our results will promote the development of 1D topological photonic devices.

Tunable Topological Acoustic Tamm States in Comblike Structures Based on Band Inversion around Flat Bands

“…In 1D periodic systems, the topology of the bands is characterized by the concept of Zak phase, a special kind of Berry phase [24][25][26][27][28]. Recently, topological interface states and Zak phase have been extended to various branches of physics such as photonics [26,[29][30][31][32][33][34], plasmonics [22,35], acoustics and mechanical systems [36][37][38][39] and metamaterials [40,41]. The topological invariant has been successfully applied to predict the existence of interface states from the Zak phases of bulk bands.…”