Open AccessObservation of terahertz plasmon and plasmon-polariton splitting in a grating-coupled AlGaN/GaN heterostructure
Author(s) -
Yu Yao,
Zhongxin Zheng,
Hua Qin,
Jiandong Sun,
Yongdan Huang,
Xinxing Li,
Zhipeng Zhang,
Dongmin Wu,
Yong Cai,
Baoshun Zhang,
В. В. Попов
Publication year - 2018
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.26.031794
Subject(s) - plasmon , terahertz radiation , materials science , surface plasmon polariton , optoelectronics , polariton , surface plasmon , surface plasmon resonance , grating , optics , photomixing , localized surface plasmon , physics , far infrared laser , laser , terahertz metamaterials , nanoparticle , nanotechnology
Plasmon in two-dimensional electron gas (2DEG) has long been considered as a promising active medium for terahertz emitters and detectors. However, the efficiency of terahertz plasmonic devices is severely limited by the high damping rate of plasma wave in solid state. In addition to the enhancement of plasmon lifetime by using 2DEGs with higher carrier mobility, engineering on the boundary condition and electromagnetic environment of plasmon cavity helps to preserve the plasmon states. Here we report on terahertz reflection spectroscopy of plasmon states in a grating-coupled AlGaN/GaN-2DEG plasmonic device at 7 K in equilibrium with ambient blackbody irradiation. Localized plasmon states and plasmon-polariton states were observed when the core plasmonic device is integrated with a silicon lens and when it is embedded in a terahertz Fabry-Pérot cavity, respectively. Simulation results including the reflection spectra and total reflection power agree well with the measured results. The Rabi splitting is found to be inversely proportional to the resonance frequency, and follows a linear relation with the square root of the sheet electron density. A normalized coupling ratio, Ω R ω 0 ≈0.13, is achieved between the Rabi splitting Ω R and the resonance frequency ω 0 . The coupling ratio could be further increased to allow for ultrastrong coupling between terahertz photons and plasmons.