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© 2025 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.

Abstract

A switchable enhancement group delay in the terahertz band based on a novel sandwich topology protection structure with graphene is proposed in this paper. The notable phase transition of the reflected beam comes from the topological edge-protected mode excited at the sandwich photonic crystal surface, and the non-trivial topology of the photonic crystal allows the structure to be immune against defects and imperfections, which lays the foundation for the enhancement of group delay in the terahertz band. And the introduction of graphene creates favorable conditions for the reversible switching of positive and negative reflection group delay. Moreover, the reflected group delay can also be flexibly and dynamically controlled by the incident angle. The positive and negative reversible switching reflected group delay proposed in the terahertz band greatly reduces the optical transmission loss and significantly increases the transmission efficiency compared with the traditional metal sandwich structure, which provides a feasible idea for the realization of multi-dimensional manipulation of the wavelength and phase of electromagnetic waves in the terahertz band. The novel scheme is expected to provide potential applications in fields such as optical buffers or ultrafast modulators.

Details

Title
Switchable Negative Group Delay Based on Sandwich Topological Protection Structure in Terahertz Band
Author
Jiao, Xu 1 ; Pan, Xianmin 1 ; Tang, Jiao 2 ; Peng, Xianghua 1 ; Peng, Yuxiang 3 

 School of Information Science and Engineering, Hunan Women’s University, Changsha 410004, China; [email protected] (J.X.); [email protected] (X.P.) 
 School of Physics and Electronics, Hunan Normal University, Changsha 410081, China; [email protected] 
 Hunan Province Key Laboratory of Materials Surface & Interface Science and Technology, Institute of Mathematics and Physics, Central South University of Forestry and Technology, Changsha 410004, China 
First page
251
Publication year
2025
Publication date
2025
Publisher
MDPI AG
e-ISSN
20794991
Source type
Scholarly Journal
Language of publication
English
ProQuest document ID
3171120299
Copyright
© 2025 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.