  Quasi-phase-matching for efficient backward second-harmonic generation (BSHG)
requires sub-$\rm\mu$m poling periods, a non-trivial fabrication feat. For the
first time, we report integrated first-order 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.
