Multidimensional Photodetection with a Broadband‐Sensitive and Polarimetric TiS ₃ /In ₂ S ₃ Heterojunction

ABSTRACT The integration of broadband, polarization‐sensitive, and ultrasensitive detection into a single photodetector is highly desirable for multidimensional optoelectronics but remains challenging. This work reports a van der Waals heterojunction photodetector based on non‐layered 2D In ₂ S ₃ and TiS ₃ that overcomes this limitation. The device operates across an ultraviolet‐to‐near‐infrared spectrum (365–1064 nm) and sets a new benchmark by unifying an exceptional detectivity (1.4 × 10 ¹⁴ Jones), a strong polarization anisotropy (3.42), fast response speed (404/789 µs), and femtowatt‐level noise‐equivalent power (28.2 fW/Hz ^1/2 ) at 405 nm. We reveal that unilateral depletion‐induced photogating effect is responsible for this superior performance, enabling high photoconductive gain without compromising speed. Capitalizing on these advanced capabilities, we further demonstrate its application in multidimensional photodetection, including broadband imaging, polarization‐resolved imaging, and ultralow power imaging at 0.23 pW. Furthermore, a two‐channel optical communication system is implemented using intensity and polarization as independent information carriers, underscoring its potential to enhance data transmission capacity. This work breaks the pervasive performance trade‐offs and provides a versatile platform for future multidimensional optoelectronic systems.