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

Abstract

The reflected group delay from a multilayer structure comprising a one-dimensional photonic crystal coated with a bulk Dirac semimetal (BDS) separated by a spacer layer is investigated theoretically. It is shown that the group delay of the reflected beam in this structure can be significantly negatively enhanced and switched from negative to positive. The enhanced group delay originates from the steep phase change caused by the excitation of the optical Tamm state at the interface between the BDS and spacer layer. Moreover, positive and negative group delays can be actively tuned through the Fermi energy and the relaxation time of the BDS. We believe that this enhanced and tunable delay scheme has important research significance for the fabrication of optical delay devices.