Second harmonic generation in reverse-proton-exchanged waveguides fabricated in periodically-poled stoichiometric lithium tantalate

In this paper, we will examine second harmonic generation in buried waveguides created through reverse-proton-exchange in periodically-poled stoichiometric lithium tantalate. Waveguides of various widths were fabricated on a 2.5cm long SLT sample provided with 5 poling periods ranging from 17.7 to 18.5/spl mu/m. The fabrication parameters were chosen according to the modelling guidelines recently proposed, in order to obtain single-mode propagation at 1.55/spl mu/m with good fiber mode-matching. The proton-exchange was performed in pure benzoic acid at 280/spl deg/C for 1h 45m, followed by annealing in air at 350/spl deg/C for 3h. The burying step was achieved by a reverse-exchange process involving the immersion of the sample for 25h at 350/spl deg/C in an euthectic melt composed by LiNO/sub 3/, KNO/sub 3/ and NaNO/sub 3/. The nonlinear characterization was performed by measuring the second harmonic generation efficiency as a function of the wavelength.