Layer number dependent Second Harmonic Generation in NbOCl₂

We report Second Harmonic Generation (SHG) measurements in both transmission and reflection geometries on few-layer NbOCl₂, a recently discovered polar van der Waals material with strong in-plane anisotropy. In contrast to transition metal dichalcogenides (TMDs) and hBN, where even layer (bilayer) structures restore inversion symmetry and suppress electric-dipole SHG, NbOCl₂ maintains a noncentrosymmetric space group across different layer numbers. Consequently, both odd- and even-layer NbOCl₂ exhibit strong SHG. In this poster presentation, we will show a comprehensive analysis on how interlayer coupling impacts SHG in few-layer NbOCl2, and discuss its comparison to the results of TMDs.