  Surfaces covered with layers of ultrathin nanoantenna structures, so-called
metasurfaces, have recently been proven capable of completely controlling phase
of light. Metalenses have emerged from the advance in the development of
metasurfaces providing a new basis for recasting traditional lenses into thin,
planar optical components capable of focusing light. The lens made of arrays of
plasmonic gold nanorods were fabricated on a glass substrate by using electron
beam lithography. A 1064 nm laser was used to create a high intensity
circularly polarized light focal spot through metalens of focal length 800
$\mu$m, $N.A. = 0.6$ fabricated based on Pancharatnam-Berry phase principle. We
demonstrated that optical rotation of birefringent nematic liquid crystal
droplets trapped in the laser beam was possible through this metalens. The
rotation of birefringent droplets convinced that the optical trap possesses
strong enough angular momentum of light from radiation of each nanostructure
acting like a local half waveplate and introducing an orientation-dependent
phase to light. Here, we show the success in creating a miniaturized and robust
metalens based optical tweezers system capable of rotating liquid crystals
droplets to imitate an optical motor for future lab-on-a-chip applications.
