2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/83318We analyze second-harmonic generation (SHG) at a thin effectively quadratic nonlinear interface between two linear optical media. We predict multistability of SHG for both plane and localized waves, and also describe two-color localized photonic modes composed of a fundamental wave and its second harmonic coupled together by parametric interaction at the interface.4 pages, 5 figures (updated references)Pattern Formation and Solitonstext