Coupled-mode analysis of second harmonic generation in the form of Cerenkov radiation from a channel optical waveguide

Optical second-harmonic generation (SHG) in the form of Cerenkov radiation from a channel waveguide is analyzed by a coupled-mode theory. A simple formula is given which expresses the SHG efficiency in terms of waveguide and optical nonlinear parameters and by which one can simulate the radiation pattern of SHG. Computational examples are plotted for LiNbO/sub 3/ crystals and reasonably agree with reported results. The analysis shows that the efficiency could be increased significantly if the sign of a d-constant in a substrate were modulated with a proper period.>