Energy‐Flux‐Weighted Absorption Designed Metallic Gratings Enable Polarization‐Sensitive Perovskite Photodiodes at the O‐Band Wavelength

Polarization‐sensitive photodetectors operating in the O‐band spectrum are essential for advanced optoelectronic applications. However, mostly metal halide perovskite photodetectors lack intrinsic polarization sensitivity and are typically limited to the UV–vis spectrum by their bandgaps. Here, O‐band spectrum polarization‐sensitive photodetection is firstly achieved by integrating an erbium‐doped bimetallic perovskite Cs 2 NaBiI 6−y Cl y :Er with energy‐flux‐weighted absorption (EFWA) designed metallic gratings. This design enables effective light field confinement and maximal absorption within the perovskite layer by selectively excite a transverse electric (TE) guided‐mode resonance (GMR) at 1310 nm, resulting in a polarized absorption of 16.14%, corresponding to a 6.86‐fold enhancement compared with their planar counterpart. Experimentally, the photodiode exhibited a record polarization anisotropy ratio of 2.31 at 1310 nm which is the longest wavelength reported so far, a responsivity of 2.14 × 10 −2 mA W −1 , and a detectivity of 1.02 × 10 7 Jones. This work provides a useful strategy to overcome the polarization discrimination limitation of perovskite photodiodes in O‐band spectrum.