Frequency-doubling in femtosecond laser inscribed periodically-poled potassium titanyl phosphate waveguides

Frequency doubling has been achieved in femtosecond-laser-inscribed single-mode waveguides written in two periodically-poled potassium titanyl phosphate crystals. A conversion efficiency of 0.22 %W(1) was obtained for first-order quasi-phase matching at 980 nm and an efficiency of 0.02 %W(-1) for third-order quasi-phase matching at 800 nm.