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Critical Coupling and Perfect Absorption Using α‐MoO 3 Multilayers in the Mid‐Infrared
Author(s) -
Dong Daxing,
Liu Youwen,
Fu Yangyang
Publication year - 2021
Publication title -
annalen der physik
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.009
H-Index - 68
eISSN - 1521-3889
pISSN - 0003-3804
DOI - 10.1002/andp.202000512
Subject(s) - materials science , absorption (acoustics) , phonon , molybdenum trioxide , polariton , condensed matter physics , optoelectronics , semiconductor , infrared , van der waals force , photonic crystal , optics , molecular physics , physics , molybdenum , quantum mechanics , metallurgy , molecule
α‐Phase molybdenum trioxide(α‐MoO 3 ) is a biaxial van der Waals semiconductor that can naturally support anisotropic phonon polaritons with elliptic and hyperbolic in‐plane dispersion. α‐MoO 3 can meet critical coupling (CC) condition for both transverse magnetic (TM) and transverse electric (TE) polarizations along the x and y directions and exhibit high absorption in the mid‐infrared region due to strong phonon polaritons. In this study, an absorber composed of few‐layer α‐MoO 3 and one‐dimensional photonic crystal separated by a cavity is proposed. Perfect absorption for TE and TM polarized light is achieved at the longitudinal and transverse optical phonon frequencies, respectively. The underlying mechanism of perfect absorption is investigated by using coupled mode theory and simulating electric field and power dissipation profiles. The results prove that CC is responsible for the perfect absorption. Moreover, the influence of the thickness of α‐MoO 3 layer, width of cavity between α‐MoO 3 and photonic crystal, and angle of incident light on the CC and absorption performance are examined. Accordingly, the rules for realizing perfect absorption at different operation frequencies are established. Overall, this study provides useful insights on designing a perfect absorber based on α‐MoO 3 for detection and sensing applications in the mid‐infrared region.