PUSH-PULL INTEGRATED-OPTICS MACH-ZEHNDER INTERFEROMETER WITH DOMAIN INVERSION IN ONE BRANCH

We report on a push-pull integrated-optics Mach-Zehnder interferometer having one domain-inverted branch and one noninverted branch. It is f abricated in the c(+) side of a LiNbO3 substrate. We achieve ferroelec tric domain inversion in one branch of the waveguide by doping it more heavily with Ti than the other branch and by using a high-temperature treatment that raises the temperature above the doped Curie temperatu re of the one branch but not of the other. The cumulative electro-opti c effect of the inverted branch is found to be opposite that in the no ninverted branch when both are subjected to the same electric field.