Optical multiplication using a bisected intersecting waveguide

We present an analysis of a bisected intersecting waveguide in periodically poled lithium niobate that can produce and isolate the second-order optical product E(/spl omega//sub 1/+/spl omega//sub 2/)/spl sim/E/sub 1/(/spl omega//sub 1/)E/sub 2/(/spl omega//sub 2/) free from the near degenerate second harmonics. Model calculations of such a device fabricated in quasi-phase matched (QPM) LiNbO/sub 3/ predict a conversion efficiency of /spl ap/1.5%/W, about 15% that of a straight waveguide of the same length, and a crosstalk of /spl lsim/-30 dB.