Design of broadband achromatic metasurface device based on phase-change material Ge2Sb2Te5

Based on the phase-change material Ge2Sb2Te5 (GST), achromatic metasurface optical device in the longer-infrared wavelength is designed. With the combination of the linear phase gradient GST nanopillar and the adjustment of the crystalline fraction m value of GST, the polarization insensitive achromic metalenses and beam deflector metasurface within the longer-infrared wavelength 9.5 mu m to 13 mu m are realized. The design results show that the achromatic metalenses can be focused on the same focal plane within the working waveband. The simulation calculation results show that the full-width at half-maximum (FWHM) of the focusing spot reaches the diffraction limit at each wavelength. In addition, the same method is also used to design a broadband achromatic beam deflector metasurface with the same deflection angle of 19 degrees. The method proposed in this article not only provides new ideas for the design of achromatic metasurfaces, but also provides new possibilities for the integration of optical imaging, optical coding and other related optical systems.

Automated summary

This article presents the design of achromatic metasurface optical devices based on the phase-change material Ge2Sb2Te5 (GST), enabling focusing and beam deflection in the longer-infrared wavelength range. By adjusting material properties and crystalline fraction, polarization-insensitive achromatic metalenses and beam deflectors are achieved. This approach provides new ideas for designing achromatic metasurfaces and potential integration in optical imaging and coding systems.