Enhanced and controllable reflected group delay based on Tamm surface plasmons with Dirac semimetals

TL;DR

This paper demonstrates a theoretical method to enhance and actively control the reflected group delay in a multilayer structure using Tamm surface plasmons with Dirac semimetals, enabling tunable optical delay devices.

Contribution

It introduces a novel structure combining Dirac semimetals and photonic crystals to achieve tunable and enhanced reflected group delay via Tamm plasmons.

Findings

Significant negative and positive group delay can be achieved and switched.

Group delay is tunable through Fermi energy and relaxation time.

Potential applications in optical delay devices at middle infrared band.

Abstract

In this paper, the reflected group delay from a multilayer structure where Dirac semimetal is coated on one-dimensional photonic crystal (1D PC) separated by a spacer layer is investigated theoretically. It is shown that the group delayof reflected beam in this structure can be significant enhanced negatively and can be switched from negative to positive. The enhanced group delay originates from the steep phase change caused by the excitation of Tamm plasmons at the interface between the Dirac semimetal and spacer layer. It is clear that the positive and negative group delay can be actively tuned through the Fermi energy and the relaxation time of the Dirac semimetal. We believe this enhanced and tunable delay scheme is promising for fabricating optical delay devices and other applications at middle infrared band.