Thermally Controlled Broadband Ge2Sb2Te5-Based Metamaterial Absorber for Imaging Applications

In this paper, we theoretically and numerically demonstrate a thermally controlled broadband absorber based on the phase change material Ge2Sb2Te5 (GST). When GST operates in the amorphous state, the proposed metamaterial acts as a broadband nearly perfect absorber. The absorption can reach more than 90% in the wavelength range from 0.9 to 1.41 mu m. As an application of the GST-based metamaterial absorber, the near-field imaging effect is achieved by using the intensity difference of optical absorption. Moreover, the thermally controlled switchable imaging can be performed by changing the phase transition characteristics of GST, and the imaging quality and contrast can be adjusted by changing the geometrical parameters. This designed metamaterial may have potential applications in near-infrared temperature control imaging, optical encryption, and information hiding.