Research Article

Ultra-broadband and tunable infrared absorber based on VO₂ hybrid multi-layer nanostructure

¹ School of Optical-Electrical and Computer Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China
² Shanghai Key Laboratory of Modern Optical System, Shanghai 200093, China

^* Corresponding author: liyi@usst.edu.cn

Received: 20 August 2022
Accepted: 5 December 2022

Abstract

We propose an ultra-broadband near- to mid-infrared (NMIR) tunable absorber based on VO₂ hybrid multi-layer nanostructure by hybrid integration of the upper and the lower parts. The upper part is composed of VO₂ nanocylinder arrays prepared on the front illuminated surface of quartz substrate, and VO₂ square films and VO₂/SiO₂/VO₂ square nanopillar arrays prepared on the back surface. The lower part is an array of SiO₂/Ti/VO₂ nanopillars on Ti substrate. The effects of different structural parameters and temperature on the absorption spectra were analyzed by the finite-difference time-domain method. An average absorption rate of up to 94.7% and an ultra-wide bandwidth of 6.5 μm were achieved in NMIR 1.5–8 μm. Neither vertical incident light with different polarization angles nor large inclination incident light has a significant effect on the absorption performance of the absorber. The ultra-broadband high absorption performance of this absorber will be widely used in NMIR photodetectors and other new optoelectronic devices.