Open AccessSwitchable broadband terahertz spatial modulators based on patterned graphene and vanadium dioxide
Author(s) -
Longfang Ye,
Xueer Chen,
Chunhui Zhu,
Weiwen Li,
Yong Zhang
Publication year - 2020
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.406090
Subject(s) - graphene , materials science , transmittance , terahertz radiation , optoelectronics , absorbance , optics , modulation (music) , absorption (acoustics) , nanotechnology , physics , acoustics , composite material
We numerically demonstrate a switchable broadband terahertz spatial modulator composed of ginkgo-leaf-patterned graphene and transition material vanadium dioxide (VO 2 ). The phase transition property of VO 2 is used to switch the spatial modulator from absorption mode to transmission mode, and the graphene behaves as dynamically adjustable material for a large scale of absorption and transmittance modulation. When VO 2 is in the metallic state and the Fermi energy of graphene is set as 0.8 eV, the proposed modulator behaves as a broadband absorber with the absorbance over 85% from 1.33 to 2.83 THz. By adjusting the graphene Fermi level from 0 to 0.8 eV, the peak absorbance can be continuously tuned from 24.3% to near 100% under the absorption mode, and the transmittance at 2.5 THz can be continuously tuned from 87% to 35.5% under the transmission mode. To further increase the bandwidth, a three-layer-patterned-graphene is introduced into a new modulator design, which achieves a wide bandwidth of 3.13 THz for the absorbance over 85%. By the combination of the tunability of graphene and VO 2 , the proposed modulators not only can flexibly switch between dual-functional modulation modes of absorption and transmission but also possess deep modulation depth. Benefitting from the excellent modulation performance, the proposed switchable dual-functional spatial modulators may offer significant potential applications in various terahertz smart optoelectronic devices.