Strong anisotropy of multilayer γ-InSe-enabled polarization division multiplexing photodetection

Abstract

Polarized light detection is consequential for optical communication and polarized light imaging. InSe is considered a promising candidate for narrowbandgap photodetector. However, monolayer.-InSe is an indirect bandgap semiconductor and is ignored for a long time for polarized light detection. In this work, by virtue of the indirect-direct conversation and the surface-bound excitons, the intrinsic anisotropy of multilayer.-InSe is revealed by the photoluminescence (PL) measurement under polarized light. Due to the anisotropy of surface-bound exaction and in-plane exciton, there are significant differences in the photocurrent under irradiation of laser with different polarization angles. The.-InSe-based photodetector exhibits considerable polarization-dependent photocurrent with an outstanding anisotropic ratio of 2.7. Moreover, the multilayer.-InSe photodetector shows high responsivity of 7.47 AW(-1) and specific detectivity of 4.56 x 1013 Jones under 785 nm laser. Based on the InSe polarization photodetector, a polarization division multiplexing that can simultaneously process four information tracks and enhance the communication speed by 24 is explored. The multilayer InSe polarization photodetector proposed in this work broadens a new path for polarized light detection, and brings a potential solution to the field of optical communications.