Plasmonic terahertz modulator based on a grating-coupled two-dimensional electron system

Electrically driven broadbandmodulator with large modulation depth and high speed is in high demand to meet the technical advancing and applications interahertz fields recently. So far, the single-particle non-resonant absorption mechanism described by the Drude conductivity has been utilized in most of the related researches but is still not efficient enough. Here we proposed and demonstrated a terahertzmodulator based on the collective electron plasma excitations(plasmons) in a grating-coupled two-dimensionalelectron gas in GaN/AlGaNheterostructure. By switching between the resonant and non-resonant conditions of the 2Dplasmon excitation enabled by applying proper gate biases, the transmission of terahertz electromagnetic waves can be efficiently manipulated. Taking advantage of its resonant characteristic combined with the strongelectric field enhancement in the active region, we experimentally achieved a maximum intensity modulation depth of 93%, a 3  dB operation bandwidth of ∼400 kHz, and a small required driving voltage amplitude of 2 V at a cryogenic temperature of 8.7 K. Owing to its excellent performances, this active plasmon-based terahertzmodulator may offer some promising solutions in several fields of terahertz technology in the future.

Source: Applied Physics Letters - November 17, 2016 Category: Physics Authors: Y. D. Huang, Y. Yu, H. Qin, J. D. Sun, Z. P. Zhang, X. X. Li, J. J. Huang and Y. Cai Source Type: research