Periodically poled ridge waveguides in KTP for second harmonic generation in the UV regime

Waveguide circuits play a key role inmodern integrated optics and provide an appealing approach to scalability in quantum optics. We report on periodically poled ridge waveguides in z-cut potassium titanyl phosphate (KTiOPO4 or KTP), a material that has recently received growing interest due to its unique dispersion properties. Ridges were defined in surface-near rubidium-exchanged KTP by use of a precise diamond-blade dicing saw. We fabricated singlemode ridge waveguides at around 800 nm which exhibit widths of 1.9-3. 2μm and facilitated type-II second harmonic generation from 792 nm to 396 nm with high efficiency of 6.6%/W·cm2. Temperature dependence of the second harmonic process was found to be 53 pm/K. 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