Full‐Stokes Photodetector Based on TiO 2 Metasurface

Abstract Polarization detection plays a critical role in diverse application fields such as target identification, remote sensing, and biomedicine. Full‐Stokes detection is the most comprehensive characterization of the polarization state of light. While full‐Stokes photodetectors based on metallic metasurfaces have been widely explored, their performance is constrained by the intrinsic absorption losses of metallic materials. Titanium dioxide (TiO 2 ) has emerged as a promising material for metasurfaces due to its superior combination of high refractive index and low absorption losses. This work presents a high‐performance full‐Stokes photodetector based on TiO 2 metasurfaces. Using an integrated four‐pixel structure combining TiO 2 nanowire gratings and chiral metasurfaces, polarization‐dependent transmission is successfully measured for arbitrary input polarization states. Experimental results demonstrate full‐Stokes detection at 780 nm wavelength, with a circular dichroism (CD) of ≈18%. The reconstructed full‐Stokes parameters exhibit good agreement with the theoretical values across various linear, elliptical, and circular polarization states, with average measurement errors of 13.8%, 19.4%, and 17.9% for S 1 , S 2 , and S 3 , respectively. The proposed design offers a promising solution for integrated full‐Stokes detection in compact, Complementary Metal‐Oxide‐Semiconductor (CMOS)‐compatible systems for the visible to near‐infrared wavelength range.