FREQUENCY DOUBLING IN ION-IMPLANTED KTIOPO4 PLANAR WAVE-GUIDES WITH 25-PERCENT CONVERSION EFFICIENCY

Second-harmonic generation (SHG) has been successfully performed in ion-implanted planar waveguides in KTiOPO4. The waveguides were formed by helium implantation, and SHG was achieved using type 2 zero order mode phase matching at a wavelength of approximately 1.07 mum. The results indicate that the high nonlinearity of the material remains in the guiding region after ion implantation. The conversion efficiency in a typical guide is estimated at approximately 25% for approximately 1 muJ pulsed excitation. At a lower input power level, the harmonic green output from the waveguide is 20 times higher than that from the bulk for the same amount of fundamental power. This clearly demonstrates the advantage of using waveguides in achieving frequency doubling for integrated optical devices.