Polar enhancement of optical nonlinearities and domain-driven second harmonic contrast in bismuth telluro-halide van der Waals crystals
The BiTeX family of polar van der Waals (vdW) semiconductors offers a unique platform for exploring the interplay between polar crystalline structure and nonlinear optical phenomena. Here, we utilize second harmonic generation (SHG) polarimetry to demonstrate giant anisotropic optical nonlinearities in BiTeBr and BiTeI driven by...