Abstract
We report on the observation of an exalted second-harmonic generation process related to a resonant effect inside a GaN photonic crystal slab. The measured enhancement factor, close to 104, is the highest measured in this photonic crystal slab resonant configuration. This frequency conversion process is also successfully compared to a rigorous modeling using a scattering matrix formalism. In addition, an original polarization study is proposed, leading to an evaluation of the relative contributions of the fundamental and the second-harmonic modes resonances in the second-harmonic response magnitude.