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

Waveguide circuits play a key role in modern 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 single-mode ridge waveguides at around 800 nm which exhibit widths of 1.9-3.2 mu m and facilitated type-11 second harmonic generation from 792 nm to 396 nm with high efficiency of 6.6 %/W.cm(2). Temperature dependence of the second harmonic process was found to be 53 pm/K. The low temperature dependence and high nonlinear conversion efficiency make our waveguides ideally suited for future operations in classical nonlinear integrated optics and integrated quantum networking applications. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement