Broadband infrared plasmonic metamaterial absorber with multipronged absorption mechanisms

A broadband plasmonic metamaterial absorber with near perfect multiband absorption in the infrared region is designed using a metal-insulator-metal configuration and fabricated using photolithography. The metal-insulator-metal configuration consists of a Ti microdisk array, a SiO2 insulator spacer, and an Al bottom layer. The multiband absorption occurs with near perfect absorption at 4.8-7.5 mu m and 9.7-10.5 mu m. Ultra-broadband absorption in the mid-IR wavelength range between 3-14 mu m is realized by adding a rough photoresist layer on top of the periodic microdisk structures. The multiband absorption is achieved through the combined mechanisms including plasmonic surface lattice resonance, gap plasmon resonance, Fabry-Perot cavity resonance, and the intrinsic phonon-polariton absorption of SiO2. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement