Quasi-phase matched second harmonic generation in periodically poled Rb-doped KTiOPO₄ ridge waveguide

A 10.8 µm wide ridge waveguide was fabricated by diamond-blade dicing in an ion-exchanged periodically poled Rb-doped KTiOPO₄ sample. The waveguide was used to generate blue second harmonic light at 468.8 nm in the TM₀₀ mode through first order Type I quasi-phase matching, exploiting the large d₃₃ coefficient of the crystal. It was evaluated using a cw Ti:Sapphire laser, and 6.7 µW of blue light was generated with 5.8 mW of fundamental radiation at 933.8 nm coupled through the waveguide. The results presented here pave the way for efficient nonlinear processes in a waveguide format.