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

Abstract

Quasi-phase-matching for efficient backward second-harmonic generation (BSHG) requires subµm poling periods, a non-trivial fabrication feat. For the first time, we report integrated firstorder quasi-phase-matched BSHG enabled by seeded all-optical poling. The self-organized grating inscription circumvents all fabrication challenges. We compare backward and forward processes and explain how grating period influences the conversion efficiency. These results showcase unique properties of the coherent photogalvanic effect and how it can bring new nonlinear functionalities to integrated photonics.