Anisotropic Coupling‐Based 2D Material Dember Polarized Photodetectors

Abstract Polarization photodetectors (PPDs) based on 2D materials hold great promise for ultracompact polarimeters due to their ability to directly detect polarization states. However, the existing PPDs based on 2D materials tend to focus on a single metric, making it challenging to obtain both a large polarization ratio ( PR ) and high responsivity ( R ). Here, black phosphorus (BP) PPDs are proposed under a nanowire configuration that enables large PR and high R simultaneously. Benefitting from the anisotropic coupling between the BP crystal and the nanowire geometry, specific light‐field distributions are formed under orthogonally polarized light incidences, through selectively exciting the localized surface plasmon and leaky‐mode resonances. A large carrier concentration gradient inherent to this structure is formed to induce a high response contrast and a large Dember current, enabling an ultrahigh PR ≈ 118.4, R ≈ 802.42 A W −1 , and ultrashort response time ≈ 636 ps. Finally, a key‐free optical encryption communication system is constructed, demonstrating one of its promising applications.