Phase-matched second-harmonic generation in a Ta2O5/KTiOPO4 waveguide

Abstract
Highly efficient phase‐matched second‐harmonic generation (TEω00‐like mode to TE10‐like mode) using waveguide modal dispersions is reported. The waveguide is composed of a KTiOPO4 substrate, a Ta2O5 thin‐film core, and a SiO2 clad in the strip‐loaded configuration. Normalized conversion efficiency of around 1000%/W cm2 and the blue (413 nm) second‐harmonic power of 13 mW were achieved with a 4.1‐mm‐long waveguide. The output beam of the second‐harmonic wave showed a single‐peak power profile, in spite of being first‐order mode in the film thickness directions.