Domain dynamics in sub-µm Periodically Poled Rb-doped KTiOPO4 via coercive field engineering

Nonlinear processes involving counter-propagating waves such as backward-wave optical parametric oscillator or backward second-harmonic generation possess unique spectral and tuning properties due to the counter-propagating nature of the interaction [1] , [2] . These processes enable fascinating phenomena like, for instance, all optical switching, tunable photonic bandgaps, ultrabright biphoton sources; being of interest for a wide range of applications, from LIDAR and spectroscopy to quantum optics. However, due to the large wavevector mismatch of the interacting waves, all these interactions require QPM structures with periods on the sub-micrometer range. This poses a substantial fabrication challenge. KTiOPO 4 (KTP), due to its chiral crystal structure and domain growth anisotropy, is well suited for periodic poling of bulk gratings with sub-micrometer periodicity. Nevertheless, conventional electric field poling proved to be problematic for the fabrication of these dense structures, mainly due to the difficulty of controlling the lateral domain growth.