Third order backward second-harmonic generation in periodically poled Rb-doped KTP with a period of 317 nm

Abstract

We demonstrate 3rd order QPM backward SHG in a bulk PPRKTP with a poling period of 317nm. This is the shortest QPM period ever fabricated. These results pave the way towards 1st order BSHG.

Integrated Backward Second-Harmonic Generation Through Optically Induced Quasi-Phase Matching

“…As such, while BSHG has been studied theoretically for several configurations [30,31], there have been limited experimental demonstrations. BSHG has been achieved in bulk materials such as periodically poled lithium niobate (PPLN) [32] and potassium titanyl phosphate (KTP) using high-order QPM [33][34][35], or stacked metasurfaces [36] with first-order QPM. There is also a continuous effort to achieve BSHG in integrated photonics.…”