Dielectric Contrast Tailoring for Polarized Photosensitivity toward Multiplexing Optical Communications and Dynamic...

A selective-area oxidation strategy is developed to polarize high-symmetry 2D layered materials (2DLMs). The dichroic ratio of the derived O-WS₂/WS₂ photodetector reaches ∼8, which is competitive among state-of-the-art polarization photodetectors. Finite-different time-domain simulations consolidate that the polarization-sensitive photoresponse is associated with anisotropic spacial confinement, which gives rise to distinct dielectric contrasts for linearly polarized light of various directions and thus the polarization-dependent near-field distribution. Furthermore, selective-area oxidation treatment brings about dual effects, comprising the in situ formation of seamless in-plane WS₂ homojunctions by thickness tailoring and the formation of out-of-plane O-WS₂/WS₂ heterojunctions. As a consequence, the recombination of photocarriers is markedly suppressed, resulting in outstanding photosensitivity with the optimized responsivity, external quantum efficiency, and detectivity of 0.161 A/W, 49.4%, and 1.4 × 10¹¹ Jones for an O-WS₂/WS₂ photodetector in a self-powered mode. A scheme of multiplexing optical communications is revealed by harnessing the intensity and polarization state of light as independent transmission channels. Furthermore, dynamic encryption by leveraging the polarization state as a secret key is proposed. In the end, broad universality is reinforced through the induction of linear dichroism within 2D WSe₂ crystals. On the whole, this study provides an additional perspective on polarization optoelectronics based on 2DLMs.