Periodic poling of Rb-doped KTiOPO₄ by coercive field engineering.

We demonstrate fine-pitch periodic poling of bulk Rb-doped KTiOPO₄ using a coercive field grating induced by ion-exchange. These samples were used for quasi phase matched (QPM) second harmonic generation at 795 nm with a normalized conversion efficiency of 1.7% W^-1cm^-1. Additionally, the ion-exchange introduced a refractive index change over the sample thickness resulting in a phasematching wavelength shift of 0.21 nm, adding extra tunability to the QPM device.