
16.7.1 Electro-Optic Overlay Intensity Modulators
Extensive theoretical and experimental studies have been carried out on the
fiber optic components based on the principle of asymmetrical directional cou-
pling. In these devices, one of the waveguides can be a D-shape fiber with its flat
etched, or an optical fiber with its side cladding polished, to close proximity of
the core, and the other is a planar waveguide, which regularly has higher
refractive index. Efficient evanescent coupling from the fiber to the overlay
waveguide occurs when one of the film waveguide modes, usually highest order
mode, is matched to that of the fiber. Light coupled into ...