Dynamically switchable dual-band mid-infrared absorber with phase-change material Ge2Sb2Te5

Abstract

Spectral control of light absorption in mid-infrared (MIR) regime is of great importance from fundamental research to practical applications. A Ge2Sb2Te5 (GST)-based tunable MIR absorber by reversible phase transitions is theoretically investigated based on the rigorous coupled wave analysis (RCWA) method. The absorber is composed of subwavelength dielectric grating and GST layer sandwiched into zinc sulfide (ZnS) layer which sitting on optical glass (BK7) substrate. Dual absorption peaks can be observed and a huge contrast in the peak of absorption can be obtained by intermediate phase states of the GST layer. The presented structure acting as a perfect absorber is likely to be exploited in applications where require active control over light absorption.