Second harmonic generation in iridium and iridium/Al₂O₃ heterostructure coatings

In this work, we demonstrate the potential of iridium (Ir) and iridium/alumina (Ir/Al 2 O 3 ) based atomic-scale heterostructures as promising non-linear optical materials. We investigated the surface second harmonic generation (SHG) response from Ir nanoparticles and their heterostructures. The SHG signal from Ir increases with the surface coverage of nanoparticles but is constrained by self-absorption beyond a certain thickness. Notably, the Ir/Al 2 O 3 heterostructures demonstrate up to two orders of magnitude higher SH response than bare Ir, attributed to improved optical properties by incorporating the dielectric material. This study highlights the potential of precisely grown Ir/Al 2 O 3 metal-dielectric heterostructures based on atomically thin layers for advanced optical applications.