Anisotropic Raman Response from Isotropic Constituents in BP/MoS ₂ Heterostructures

Anisotropic layered materials (ALMs) can be integrated with isotropic materials to form van der Waals heterostructures (vdWHs) for polarization-sensitive optoelectronic applications, yet the influence of ALM optical anisotropy on the Raman response of isotropic components remains an open question. This study demonstrates that monolayer MoS2 in black phosphorus/MoS2 (BP/1LM) vdWHs exhibits pronounced in-plane anisotropic Raman responses despite its intrinsic isotropy, as revealed through angle-resolved polarized Raman (ARPR) spectroscopy. The A1′ and E′ mode intensities of the 1LM constituent display strong angular dependencies that closely mimic the anisotropic profiles of the Raman modes of BP, resulting from the birefringence and linear dichroism of BP combined with interference effects within the multilayer stack. The theoretical calculations incorporating depth-dependent field modulation and multilayer interference reproduce the experimental results and demonstrate dependence on the BP thickness and excitation wavelength. This work provides a quantitative framework for understanding and engineering optical anisotropy in heterostructures comprising isotropic and anisotropic two-dimensional materials.