Open AccessAsymmetric dielectric grating on metallic film enabled dual- and narrow-band absorbers
Author(s) -
Xin He,
Jinliang Jie,
Junbo Yang,
Yunxin Han,
Sen 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.386742
Subject(s) - optics , materials science , grating , surface plasmon , surface plasmon polariton , plasmon , angle of incidence (optics) , diffraction grating , dielectric , optoelectronics , silicon , wavelength , physics
We investigated a mid-infrared (mid-IR) dual-band absorber consisting of a continuous gold film coated with an asymmetric silicon grating. In each unit cell of the grating, there are three unequally spaced silicon strips. Numerical results reveal that the (+1, -1) planar surface plasmon polariton (SPP) waves excited by the transverse-magnetic (TM) incidence can be coupled with different Fabry-Pérot (FP) resonances and the resonant energy is dissipated to the ohmic loss. Under the normal incidence condition, the absorber provides two high-absorbance peaks at wavelengths of 3.856 µm and 4.29 µm, with the absorption bandwidths of ∼25.7 cm -1 and ∼21.5 cm -1 . When changing the angle of the incidence, it is observed an interesting feature that either of the peaks does not split. The presented structure offers an approach to the design of optical components for multi-spectral control of mid-IR signals.