COUPLED-MODE ANALYSIS OF 2ND HARMONIC-GENERATION IN THE FORM OF CERENKOV RADIATION FROM A CHANNEL OPTICAL WAVE-GUIDE

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 LiNbO3 crystals, which reasonably agrees with the reported results in the literature. 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.