In the context of nanotechnology, SHG occurs in nanoparticles, nanowires, and thin films which possess a non-centrosymmetric structure. When these nanomaterials are exposed to an intense laser field, the electric field of the light induces a polarization in the material, leading to the generation of a second harmonic signal. This process is highly dependent on the symmetry, size, and shape of the nanostructures.
