Structural Design Strategies for Polarization-Sensitive Photodetectors Using Two-Dimensional Materials

Polarization-sensitive photodetectors based on anisotropic two-dimensional (2D) materials have attracted extensive research interest in recent years. The rapid development of 2D anisotropic materials has created new opportunities for compact and broadband polarization detection of light, as their crystal anisotropy determines both optical and electronic asymmetries. This review specifically explains the intrinsic mechanisms of optical and electronic anisotropy, showing how crystal symmetry, electronic band structure, permittivity, and conductivity govern these properties. It then systematically describes experimental methods to characterize intrinsic anisotropic optical and electronic responses. It further discusses how externally engineered strategies, such as the ferroelectric modulation, photogating, and plasmonic nanostructures enhance the polarization ratio (PR). Then the review highlights key recent discoveries about how to achieve high PR through optimized material selection, principal-axis channel alignment, and external modulation of device architectures, so as to enhance the performance of polarization-sensitive photodetectors. Finally, it points out future directions and challenges in this rapidly evolving field. The physical insights and practical design guidelines provided in this review will promote the development of next-generation polarization-sensitive photodetectors.