Dynamically Tunable Plasmon-induced Transparency in a T-shaped Cavity Waveguide Based on Bulk Dirac Semimetals
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Dynamically Tunable Plasmon-induced Transparency in a T-shaped Cavity Waveguide Based on Bulk Dirac Semimetals Ting Zhou 1 & Xinyu Gou 1 & Wei Xu 1 & Yong Li 1 & Xiang Zhai 1
&
Hongjian Li 2 & Lingling Wang 1
Received: 27 May 2020 / Accepted: 1 September 2020 # Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract We propose a dynamically tunable surface plasmon polaritons (SPPs) waveguide system based on bulk Dirac semimetals (BDS) containing only a side-coupled T-shaped cavity. Plasmon-induced transparency (PIT) is achieved in the terahertz band by introducing a position offset. We have analytically investigated the spectral characteristics of PIT in this system, indicating that the larger the position offset, the higher the peak of the PIT window. The spectrum responses of PIT system can be flexibly regulated via transforming the geometric parameters of the structure. At the same time, it is particularly sensitive to the refractive index of the surrounding medium, which is promising for sensing devices. In addition, the resonance frequency and peak transmission can be actively adjusted by controlling the Fermi energy of the BDS without reconstructing the geometric structure. Moreover, the optical delay time near the PIT peak reaches 11.001 ps, which has good slow-light characteristics and is a candidate in the field of slow-light equipment. The structure we designed may have potential application value in the design of SPPs light-guide devices. Keywords Bulk Dirac semimetals . Dynamically tunable . Plasmon-induced transparency . Surface plasmon polaritons
Introduction Electromagnetically induced transparency (EIT) effect is a special interference phenomenon occurring in the quantum systems [1, 2], which has a narrow transparent window within a broader absorption band due to destructive interference. The EIT systems have great potential for slow-light, optical sensing, and optical data storage [3] because of the high group refractive index and dispersion near the transparent window. However, the EIT in quantum systems is extremely demanding on experiments and its application is limited. At present, researchers have proposed many alternatives for EIT that can occur in classical systems. Plasmon-induced transparency (PIT) is the most recent and potential * Xiang Zhai [email protected] 1
Key Laboratory for Micro/Nano Optoelectronic Devices of Ministry of Education & Hunan Provincial Key Laboratory of Low-Dimensional Structural Physics and Devices, School of Physics and Electronics, Hunan University, Changsha 410082, China
2
School of Physics and Electronics, Central South University, Changsha 410083, China
component of existing EIT-like effects [4–14]. In the past few decades, most of the research on PIT has been based on the structure of metal-insulator-metal (MIM) waveguides owing to its strong light confinement. There are two classic MIM waveguide structures, one is the phase coupling between two detuned cavities [5, 6] and the other is the coupling between the radiation mode and
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