Polarizer-free polarimetric image sensor through anisotropic two-dimensional GeSe

Light polarization could provide critical visual information (e.g., surface roughness, geometry, or orientation) of the imaged objects beyond prevailing signals of intensity and wavelength. The polarization imaging technology thus has a large potential in broad fields such as object detection. However, intricate polarization coding is often required in these fields, and the existing complicated lensed system and polarizers have limited the miniaturization capabilities of the integrated imaging sensor. In this study, we demonstrate the utilization of two-dimensional (2D) in-plane anisotropic α-GeSe semiconductor to realize the polarizer-free polarization-sensitive visible/near-infrared (VIS-NIR) photodetector/imager. As the key part of the sensor system, this prototype Au/GeSe/Au photodetector exhibits impressive performances in terms of high sensitivity, broad spectral response, and fast-speed operation (∼10³ AW⁻¹ 400–1050 nm, and 22.7/49.5 µs). Further, this device demonstrates unique polarization sensitivity in the spectral range of 690–1050 nm and broadband absorption of light polarized preferentially in the γ-direction, as predicted by the analysis of optical transition behavior in α-GeSe. Then we have successfully incorporated the 2D GeSe device into an imaging system for the polarization imaging and captured the polarization information of the radiant target with a high contrast ratio of 3.45 at 808 nm (NIR band). This proposed imager reveals the ability to sense dual-band polarization signals in the scene without polarizers and paves the way for polarimetric imaging sensor arrays for advanced applications.