Optical anisotropy in van der Waals heterostructures integrated with a low symmetry layered compound NbPS.

Two-dimensional (2D) van der Waals (vdW) materials with low crystal symmetry exhibit unique anisotropic optical and electronic properties. Here, we systematically investigate the optical modulation effects induced by anisotropic 2D materials on their isotropic counterparts in vertically stacked heterostructures. Through angle-resolved polarized Raman and photoluminescence (PL) spectroscopy of MoS/NbPS heterostructures, we observe periodic modulation of Raman and PL intensities in the intrinsically isotropic monolayer MoS, directly correlated with the crystallographic orientation of the anisotropic NbPS substrate. This phenomenon arises from strong in-plane birefringence and dichroism in NbPS, which create a polarization-dependent Fabry-Pérot cavity that dynamically tailors the optical environment of MoS cavity-mediated interference. Furthermore, we demonstrate magnetic field control of this anisotropic response through magneto-optic coupling, while polarization-resolved photocurrent measurements reveal the effect of in-plane anisotropy in NbPS on carrier transport in MoS. Our work establishes a cavity-mediated methodology to engineer light-matter interactions in isotropic 2D materials through anisotropic heterostructure design, opening avenues for developing advanced polarization-sensitive optoelectronics such as angle-resolved photodetectors and reconfigurable optical modulators.