In-plane optical anisotropy and nonlinear optical effects in 2D InTeO ₃ Cl

Anisotropic two-dimensional (2D) materials with low structural symmetry and in-plane optical anisotropy provide a promising platform for the development of polarization-driven photonic devices. Herein, high-quality subcentimetre-scale InTeO₃Cl single crystals were prepared using the chemical vapor transport (CVT) method and further exfoliated to flakes of nanometer thickness. The crystal structure, optical anisotropy, bandgap, and stability of 2D InTeO₃Cl were extensively investigated. Raman characterization verified the strong in-plane optical anisotropy of 2D InTeO₃Cl. Furthermore, it presented an optical bandgap of 2.6 eV and excellent environmental and thermal stability. Interestingly, 2D InTeO₃Cl manifested an anisotropic second-harmonic generation (SHG) response, which originated from a centrosymmetry breaking induced by periodic interlayer dislocation. Our work reveals the outstanding in-plane optical anisotropy and nonlinear optical effects of 2D InTeO₃Cl and provides a promising candidate for the development of high-performance optical and photonic devices.