Ultra-broadband visible and mid-infrared light absorber via magnetic dipole and surface plasmon resonances

Abstract

We numerically demonstrate an ultra-broadband plasmonic absorber by applying chromium and titanium in a 3D metamaterial structure. One unit cell of the proposed absorber consists of continuous Cr/SiO2 multi-layers covered by two Ti nanodisks for exciting multiple magnetic dipole resonances and localized surface plasmon resonance. The optical simulation results show that the average absorption of the plasmonic structure exceeds 98.4% in the wavelength range of 400- % in the wavelength range of 400−4000 nm. The broadband and high absorption benefits from impedance matching between the nanodisks array and the free space in the wavelength range. Through thermal simulation, we also investigated the photothermal heating generation in the plasmonic metamaterial structure. The temperature rise in the proposed structure is approximately 447 K with an incident wavelength of 618 nm and a light flux of 100 W/cm2. Due to the ultra-broadband absorbing performance, the presented design has possibilities in the fields of photodetector applications, solar energy harvesting, thermal emitters, and infrared cloaking.