Ultrathin Tunable Optomechanical Metalens

Reconfigurable metasurfaces offer great promises to enhance
photonics
technology by combining integration with improved functionalities.
Recently, reconfigurability in otherwise static metasurfaces has been
achieved by modifying the electric permittivity of the meta-atoms
themselves or their immediate surrounding. Yet, it remains challenging
to achieve significant and fast tunability without increasing bulkiness.
Here, we demonstrate an ultrathin tunable metalens whose focal distance
can be changed through optomechanical control with moderate continuous
wave intensities. We achieve fast focal length changes of more than
5% with response time of the order of 10 μs.