Annealed proton-exchanged waveguide quasi-phase-matched second-harmonic generation devices in 8 mol % MgO-doped congruent LiTaO3 crystal

Heavily (8 mol %) MgO-doped congruent LiTaO3 (MgO:cLT) crystal has wider transparency range and higher photorefractive damage resistance than LiNbO3 or non-doped LiTaO3 crystal. We examined the possibility of forming annealed proton-exchanged (APE) waveguides with various conditions. We obtained good quality APE waveguides with the propagation loss 0.7 dB/cm for 1.064 µm wavelength and demonstrated a prototype waveguide quasi-phase-matched second-harmonic generation device of 56%/W normalized efficiency for the first time in MgO:cLT crystal.