Open AccessPerfect mid-infrared dual-band optical absorption realized by a simple lithography-free polar dielectric/metal double-layer nanostructure
Author(s) -
Huijin Shen,
Yang Liu,
Yi Jin,
Sailing He
Publication year - 2020
Publication title -
optics express
Language(s) - Uncategorized
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.402851
Subject(s) - materials science , optics , dielectric , absorption (acoustics) , optoelectronics , surface plasmon , polarization (electrochemistry) , lithography , plasmon , chemistry , physics , composite material
A perfect mid-infrared dual-band absorber based on a very simple lithography-free polar dielectric/metal double-layer nanostructure is demonstrated experimentally. Silicon dioxide (SiO 2 ) is chosen as the top polar dielectric, which is deposited through room-temperature plasma enhanced chemical vapor deposition to protect the bottom metal layer. A nearly 100% absorption is obtained at the wavelength of ∼ 10 µm due to the constructive interference resonance, which is related to the SiO 2 thickness but insensitive to the light polarization or incident angle. Another enhanced absorption is observed experimentally at ∼ 8 µm under oblique incidence. Both numerical simulation and analytical calculation show that such absorption enhancement is induced by the excitation of the Berreman mode, where the refracted light propagates almost horizontally within the SiO 2 layer. Different from the interference-induced absorption, the Berreman mode induced absorption exists even for a very thin absorber and is sensitive to the light polarization and incident angle.