Photo-induced SHG as a sensitive tool for the detection of surface morphology for iron garnet derivative films deposited on GGG substrates

The influence of surface morphology on the photo-induced optical second harmonic generation (SHG) is established for specific iron garnet films deposited on (111) and (100) planes of the Gd₃Ga₅O₁₂ substrate, respectively. The anisotropy of the film surface is assigned to the substrate crystallographic plane used. It is shown that the decrease of the film's mean grain size enhances the output SHG signal. The increase of the mean grain size from 30 nm up to the 46 nm leads to a decrease of the photo-induced SHG (up to 30%). This could be used for the contactless diagnostic of garnet films' morphology.