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Small-sized long wavelength infrared absorber with perfect ultra-broadband absorptivity
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DOI：10.1364/OE.382776.png)
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Abstract
En 中文
Two types of ultra-broadband long wavelength infrared (LWIR) absorbers with small period and super thin thickness are designed. The absorption with high absorptivity and large bandwidth is achieved through combined propagating and localized surfaced plasmon resonances. We first design a three-layer absorber with a Ti-Ge-Ti configuration, the period of the structure is only 1.4 mu m (nearly 1/8 of the center wavelength), the thickness of its dielectric is only 0.5 mu m (1/22 of the center wavelength), and the average absorption is 87.9% under normal incident from 8 mu m to 14 mu m. Furthermore, the four-layer absorber with a Ti-Ge-Si3N4-Ti configuration is designed to obtain more average absorption increasing to 94.5% from 8 mu m to 14 mu m under normal incident, the period of the structure increases to 1.6 mu m and the total thickness of dielectric increases to 0.6 mu m. The proposed absorber is polarization-independent and possesses a good tolerance of incident angle. We calculate that the average absorption of the four-layer absorber for both TE- and TM-modes still exceeds 90% up to an incident angle of theta = 40 degrees (90.7% for TE-mode, 91.9% for TM-mode), and exceed 80% up to an incident angle of theta = 60 degrees (80.2% for TE-mode, 82.1% for TM-mode). (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
Keywords:
METAMATERIAL ABSORBERS
GRAPHENE METAMATERIAL
SOLAR-ABSORBER
DESIGN