Dual-Band Coherent Perfect Absorption/Thermal

Abstract

Dual-band perfect absorption/thermal emission is shown to be a general property of an ultrathin bilayer consisting of a dielectric and a totally reflective layer if the permittivity of the dielectric can be described by Drude-Lorentz (DL) model. The two bands coexist and reside on opposite sides of the Lorentzian resonant frequency where the material loss is small. However, the perfect absorption mechanism for the two bands is distinguishably different. One band is related to Fabry-Pérot phenomenon and the surge of refractive index near the Lorentzian resonance. This band is polarization insensitive. The other band is associated with excitation of Brewster-type mode at the ϵ-near-zero (ENZ) wavelength and occurs only for p-polarized wave at oblique incidences. This mode has a fast-wave non-radiative character and propagates along the ultrathin ENZ layer superimposed on the highly reflective surface. Both bands exhibit wide-angle high emission with a small shift in their center frequencies which can be tuned by tuning the Lorentzian resonance. The resonance-enhanced dual band absorption occurs in the ultrathin DL layer at the weakly absorbing wavelengths as a consequence of an interaction between the total transmission and the total reflection. We demonstrate this phenomenon in a silicon carbide/copper bilayer. The suggested structure may have applications in biological and chemical sensors, IR sensors, thermal emission controls, thermophotovoltaics, and photodetectors.

Progress toward high-Qperfect absorption: A Fano antilaser

“…The quest toward ultimate optical absorption has also progressed under the notion of 'perfect absorption' [12][13][14][15][16][17][18][19][20][21][22], which utilizes the destructive interference between scatterings from different origins. Employing the concept of coherent perfect absorption (CPA) [23][24][25][26][27][28][29][30], the origin of perfect absorption has been explained intuitively in the context of a time-reversed laser at the lasing threshold, i.e., an anti-laser with a scattering singularity.The applications of optical absorption can be classified in terms of their spectral responses: broadband absorptions [18][19][20] for photovoltaics [5], anti-reflector, and band-stop filter, and narrowband ones [12][13][14][15][16][17] for high-Q sensor [1-3,12,13], thermal imaging [14], opto-thermal emitter [4,15,16], and absorptive switching [6]. Interestingly, although a clear description of perfect absorption can be made through the concept of an anti-laser [23], efforts to develop narrowband anti-laser have been hindered by the difficulties in achieving high-Q values; in stark contrast to a laser which supports a narrower, single-wavelength spectrum above the threshold.…”

“…The quest toward ultimate optical absorption has also progressed under the notion of 'perfect absorption' [12][13][14][15][16][17][18][19][20][21][22], which utilizes the destructive interference between scatterings from different origins. Employing the concept of coherent perfect absorption (CPA) [23][24][25][26][27][28][29][30], the origin of perfect absorption has been explained intuitively in the context of a time-reversed laser at the lasing threshold, i.e., an anti-laser with a scattering singularity.…”

Coherent perfect absorption in epsilon-near-zero ITO thin film in near infrared

“…Beyond the high loss in thicker film, nowadays perfect absorption is to search in the thin ENZ MM [16,17]. In contrary of enhanced transmission, CPA can be harvested in the ENZ regime [18]. Applying the two inputs propagation system in opposite direction, CPA is analyzed theoretically and demonstrated [19][20][21][22][23][24] in thin film resonator.…”