Being able to probe the polarization states in low-symmetry two-dimensional (2D) crystals is crucial for applications in polarization-encoded encryption and decryption. However, their polarization sensitivity is restricted by the inherent optical anisotropy. Here, we demonstrate a strategy where black phosphorus (BP) is stacked on Nb₂SiTe₄ to form a van der Waals heterostructure, realizing a self-powered, broadband, and highly polarization-sensitive photodetector. The atomically sharp and clean interface of BP/Nb₂SiTe₄ heterostructures forms a strong built-in electric field, which facilitates the separation of electron–hole pairs. Furthermore, angle-dependent Raman and absorption intensities reveal significant anisotropic optical response. The BP/Nb₂SiTe₄ photodetector exhibits a rapid response time and broadband detection capability from 360 to 2200 nm due to the efficient charge separation and strong interlayer coupling at the heterostructure interface. Notably, the BP/Nb₂SiTe₄ device also exhibits a large dichroic ratio (10.4) at zero voltage under 2200 nm light illumination. Furthermore, the proof-of-concept BP/Nb₂SiTe₄ photodetector possesses polarization-resolved imaging and polarization-encoded encryption/decryption capabilities, providing new insights for achieving low-power and multifunctional polarization-sensitive photodetectors.

Monolayer (1L) transition metal dichalcogenides (TMDCs) have been attracting tremendous interest in recent years as promising candidate materials in atomic-scale optoelectronic devices due to their direct band gaps (1.5–2.2 eV) and strong light–matter interactions. Unfortunately, their practical applications are limited by low visible light absorption stemming from atomic thickness and negligible infrared response. Here, we report the triangular Sb₂O₃ microresonators in wide thickness and lateral size distributions grown on 1L TMDCs and their created significant broadband enhancement of light adsorption and photoresponse in 1L WSe₂ crystal via coexisting Fabry–Perot and whispering gallery type resonances. As an example of demonstration, 1L WSe₂ crystal coupled to Sb₂O₃ microresonators with widely distributed sizes exhibits the enhanced visible light absorption by up to 5 folds and the simultaneously extended near infrared (NIR) one of more than 50%. For application of 1L WSe₂ in photodetection, incorporation of Sb₂O₃ microresonators leads to significantly enhanced visible light responsivity by ~ 10⁴ order and expanded NIR one of more than 400 mA·W⁻¹. Similar results have been observed in the other 1L W(Mo) dichalcogenides coupled to Sb₂O₃ microresonators. This work provides a new route for development of the high-performance monolayer TMDCs-based optoelectronic devices.