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

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 mu m were achieved in NMIR 1.5-8 mu m. 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.

Automated summary

We propose an ultra-broadband tunable absorber for near- to mid-infrared (NMIR) based on a VO2 hybrid multi-layer nanostructure. The absorber consists of VO2 nanocylinder arrays on the front surface of a quartz substrate, VO2 square films and VO2/SiO2/VO2 square nanopillar arrays on the back surface, and SiO2/Ti/VO2 nanopillars on a Ti substrate. The absorber achieved an average absorption rate of up to 94.7% and an ultra-wide bandwidth of 6.5 μm in the NMIR range of 1.5-8 μm. The absorber shows no significant decrease in absorption performance when exposed to vertical incident light with different polarization angles or large inclination incident light. This ultra-broadband high absorption performance makes the absorber suitable for NMIR photodetectors and other optoelectronic devices.