Nonreciprocal-Like Chiral Second-Harmonic Generation in a Chiral 3R-MoS ₂ Metasurface

Breaking reciprocity in nonlinear optics offers a unique approach for directional control of information processing. Here, we report for the first time a chiral 3R-MoS₂ metasurface that enables nonreciprocal-like chiral second-harmonic generation (SHG) via nonreciprocal circularly polarized (CP) absorption. The metasurface supports Mie resonances due to the high refractive index of 3R-MoS₂. With CP incidence around the resonant wavelength on the top surface, right-handed circular polarization (σ₊) absorption is significantly stronger than left-handed circular polarization (σ₋), leading to chiral SHG with a circular dichroism (SHG-CD) of 62%. Reversing the incidence direction inverts the absorption contrast, yielding an SHG-CD of -71%. Physically, such an optical response originates from both the intrinsic C3v symmetry of 3R-MoS₂ and the structural chirality of the metasurface. Leveraging this property, we further demonstrate four optical logic operations, AND, OR, A ANDNOT B, and A ORNOT B, revealing the metasurface as a multifunctional, polarization-dependent platform for optical logic.