ABSTRACT
Dual-band infrared absorbers have received a great deal of attention for their potential applications in the field of sensing and detection. In this paper, we proposed a composite model consisting of Platinum nano-cylinder and micro-ring column stacked on top of Si3N4and Platinum films. The effect of geometrical parameters on spectral absorption was explored by finite difference in time domain methods, and the results revealed that there were narrow perfect absorption peaks in each of the two atmospheric window bands due to the magnetic polaritons. Meanwhile, the quantitative relationship of resonance wavelength and geometrical parameters were predicted by LC equivalent circuits. In addition, graphene was added to the structure to dynamically adjust the resonance wavelength by varying the Fermi level. The combination of graphene and microstructure achieved full coverage detection of wavelengths in the atmospheric window range. This dual-band absorber has potential applications in infrared detection because of its good absorption properties and its tunability.
ABSTRACT
In this paper, a 2D periodic structure made of tungsten (W) grating patch on a thin Al2O3 spacer and an opaque W film is proposed, as a broadband selective thermal emitter. We numerically investigated the spectral emissivity of the structure from the deep by finite-difference time-domain method. Geometric parameters effects on the emissivity are discussed and the mechanisms of magnetic polaritons in the structure are further analyzed in detail. In addition, by adding another metal-dielectric stack upon the pre-existing grating structure, the emissivity of the composite structure can be further enhanced, and the normal emissivity exceeds 0.95 in the wavelength range of 0.65-1.95 µm, some even close to unity. Furthermore, the composite structures are found to exhibit insensitivity to polar angle and polarization.
