Bi-colour spatial solitons in linearly uncoupled planar waveguides

L. Colace, G. Leo, A. Amoroso, A. Di Falco, A. C. Cino, and G. Assanto

J. Opt. B: Quantum Semiclass. Opt. 6, S217-S222 (2004)


We report on the observation of spatial optical simultons in a novel geometry consisting of two partially overlapped, linearly uncoupled planar waveguides in lithium niobate obtained by reverse proton exchange. Two orthogonally polarized modes are coupled through an off-diagonal tensor element of the quadratic nonlinearity, giving rise to second harmonic generation and mutual trapping via cascading. This phenomenon demonstrates a balance between diffraction and self-focusing for two orthogonal modes of different waveguides, and occurs at room temperature in longitudinally uniform waveguides.