Broadband Airy Beam for Mid‐Infrared Wave Enabled by Ge3Sb2Te6 Metasurface.

As a novel phase change material, germanium antimony telluride (Ge3Sb2Te6) possesses the potential in the field of metasurface to dynamically manipulate wavefront and polarization of electromagnetic wave. In this work, Ge3Sb2Te6 meta‐atoms are designed for the generation of Airy beam. Relying on the advantage of Ge3Sb2Te6 rod and gold substrate, tunable reflective phase and amplitude of meta‐atom are realized through different rotation angles of Ge3Sb2Te6 rod. Due to the unique characteristics of Ge3Sb2Te6, meta‐atom can flexibly change between half‐wave plate and mirror reflector. As crystalline Ge3Sb2Te6 is adopted, cross‐polarized wave is generated by meta‐atom with a peak polarization conversion ratio (PCR) of 98% at 77.6 THz. On the contrary, as amorphous Ge3Sb2Te6 is employed, PCR is below 5%. Then, two exemplary metasurfaces are implemented as Airy beam generator and Airy beam focuser, and simulated results have a remarkable advantage of an overall bandwidth over 10 THz. The proposed metasurface may be applied in beam shaping and telecommunication. [ABSTRACT FROM AUTHOR]