Bidirectional Switchable Metalens Based on Phase Change Materials of GST

Abstract

Metalens can achieve more challenging functions especially dynamic regulation than traditional lens due to its unprecedented ability to manipulate light. In this paper, an approach to realizing switchable bidirectional metalens is proposed based on phase change material GST. Two geometric parameters of nanopillars were designed to demonstrate full phase modulation due to the Pancharatnam-Berry phase. According to the phase distribution, we realize the flexible control of the metalens through the transition of states. These special designs of unit structures make multi-focal point focus and two-dimensional focus also realized. In addition, the bidirectional switchable metalens have been realized through the transformation of states on a bilayer metasurface substrate. Its unique phase transition properties which are not available to previous metasurface can be applied in high quality imaging cameras, optical microscopes, lidar scanning systems, etc.

Keywords

• Metasurface
• phase change materials
• multi-dimensional focus