Flexible switchable mid-infrared metalens optical tweezer based on VO₂

Metasurface has developed rapidly since its advent because of its powerful control over electromagnetic waves, but most traditional metasurface can only passively realize a single fixed function, which limits its application and development in integrated systems. To modulate electromagnetic waves more flexibly and efficiently, here, we first propose what we believe to be a novel scheme to design a switchable metalens by utilizing the phase change materials VO 2 and double-layer metasurface modulation. The metalens designed by the proposed scheme can achieve flexible conversion between the transmitted focusing and reflected focusing through changing the phase state of VO 2 . Then, we investigate the optical force phenomenon of these metalenses, the simulation results indicating that the proposed switchable metalens can achieve stable particle manipulation under both the transmission and reflection modes. This makes it a promising device in flexible optical manipulation, and this reversible tuning will also show significant application potentials in biology, medicine, optical communication and other fields.