A long-range, high-precision, and compact transverse displacement metrology method is of crucial importance in many research areas. Recent schemes using optical antennas are limited in efficiency and the range of measurement due to the small size of the antenna. Here, we demonstrated the first prototype polarization-encoded metasurface for ultrasensitive long-range transverse displacement metrology. The transverse displacement of the metasurface is encoded into the polarization direction of the outgoing light via the Pancharatnam-Berry phase, which can be read out directly according to the Malus law. We experimentally demonstrate nanometer displacement resolution with the uncertainty on the order of 100 picometers for a large measurement range of 200 micrometers with the total area of the metasurface being within 900 micrometers by 900 micrometers. The measurement range can be extended further using a larger metasurface. Our work opens new avenues of applying metasurfaces in the field of ultrasensitive optical transverse displacement metrology.

Enhanced chiral optical responses of metamaterials have widespread applications in chiral biosensor and polarization optics. Metamaterials with intrinsic chirality are commonly composed of complicated 3D structures, which leads to significant fabrication challenges. Recent works involving planar chiral metasurfaces have demonstrated chiral optical response by symmetry breaking, but the intrinsic optical chirality at normal incidence is usually weak. Here, a dielectric chiral metasurface is designed and fabricated, and its strong intrinsic optical chirality in visible spectrum is experimentally demonstrated. Particularly, giant optical activity with zero circular dichroism can be obtained, implying that linear polarization of the incident light passing through the metasurface can be rotated. A phenomenological model is proposed to explain the chiral optical response of the metasurface based on the superposition of two chiral optical resonances in opposite handedness. The multipole decomposition of the electric fields corroborates how the high‐order multipoles are related to the chiral optical response. These results enable the development of flat compact devices to manipulate the polarization of light flexibly.