High resolution patterning of quadratic non-linear optical properties in doped photopolymer thin films

We demonstrate the patterning of the quadratic non-linear optical (QNLO) properties in a photopolymerizable resin doped with push-pull chromophores. Advantage is taken of the crosslinking process to perform the patterning directly. QNLO gratings with a period of 8.5 μm have been achieved over areas of a few cm2. This spacing is comparable to the typical visible and near infrared coherence lengths in this material and is therefore suitable for the elaboration of quasi-phase matched waveguides. An accurate characterization of the QNLO gratings has been performed using a high spatial resolution second harmonic generation microscope with a femtosecond laser source.