Soft proton exchange on periodically poled LiNbO3: A simple waveguide fabrication process for highly efficient nonlinear interactions

We report a simple fabrication process for realizing waveguides on periodic ally poled lithium niobate which preserves both the nonlinearity and the do main inversion. This so-called soft proton exchange has been used to genera te highly efficient optical parametric fluorescence in the 1.48-2.01 mu m r egion using a pump around 830 nm. The measured normalized efficiency is 130 % W-1 cm(-2) for an effective interaction length of 1.3 cm. This experiment al figure is very close to the maximum theoretically predicted value of 140 % W-1 cm(-2). (C) 2000 American Institute of Physics. [S0003-6951(00)01609- 0].