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 periodically poled lithium niobate which preserves both the nonlinearity and the domain inversion. This so-called soft proton exchange has been used to generate highly efficient optical parametric fluorescence in the 1.48-2.01 mu m region 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 experimental 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].