Tunable broadband, wide-angle, and polarization-dependent perfect infrared absorber based on planar structure...

A multilayer absorber composed of SiO₂, Fe, Ge₂Sb₂Te₅ (GST), and Al is designed, and the absorptive properties are theoretically investigated based on the Fresnel coefficients method in the wavelength range of 300-2500 nm by changing the thickness and crystallization rate of GST, the incident angle, and the polarization. The results show that the thin Fe layer plays a key role in obtaining an ultra-broadband perfect absorption. The absorption properties are polarization-dependent, and the perfect absorption can be nearly realized for a p-polarized wave at the incident angle smaller than 75° with the bandwidth larger than 316 nm at 90% of max absorption value. The absorptive peak of this absorber can be tuned with the crystallization rate of GST by temperature, and the peak wavelength moves from 1433 nm in the amorphous phase to 2051 nm in the crystalline phase. This structure can provide a feasible route to design the tunable broadband, wide-angle, and polarization-dependent perfect absorber without lithographic patterns in the infrared band.