Rapid Polarization-Controlled Depth Sensing and Imaging with an Electrically Tunable Metalens.

Kim, Yeseul; Lee, Jihae; Yeo, Wei-Hong; Li, Xiaotong; Kim, Won-Sik; Kim, Young-Ki; Badloe, Trevon; Sun, Cheng et al. · Nano Lett · 2025

basic_science · Level V

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Abstract

We demonstrate an electrically tunable metalens that combines hydrogenated amorphous silicon (a-Si:H) meta-atoms with a liquid crystal (LC) layer for rapid polarization-controlled depth sensing and imaging. Two independent focusing profiles for left-circularly polarized (LCP) light and right-circularly polarized (RCP) light are encoded via propagation and geometric phases in a single metasurface. Adjusting the LC voltage and the incident polarization among the LCP, RCP, and their superposition enables millisecond-scale reconfiguration. Under pure circular polarization, the metalens yields a single high-fidelity focal spot or an image. Linearly polarized light produces two rotating images, whose relative orientation encodes object depth. Experiments match theory and confirm a full π rotation of the image during focal scanning. The device offers a compact, real-time platform for imaging and depth sensing in microscopy, holography, and adaptive optics.