An apparatus and associated method for altering the propagation constant of
a region of changable propagation constant in an optical waveguide. The
method comprising positioning an electrode of a prescribed electrode shape
proximate the waveguide. An altered region of changable propagation
constant is projected into the waveguides that correspond, in shape, to
the prescribed electrode shape by applying a voltage to the shaped
electrode. The propagation constant of the region of changable propagation
constant is controlled by varying the voltage.
