A strip loaded waveguide comprises a slab and a strip, wherein the strip is separated
from the slab. Nevertheless, a guiding region is provided for propagating an optical
mode and this guiding region extends both within the strip and the slab. A layer
of material having an index of refraction lower than that of the strip and the
slab may be disposed between and separate the strip and the slab. In one embodiment,
the slab comprises a crystalline silicon, the strip comprises polysilicon or crystalline
silicon, and the layer of material therebetween comprises silicon dioxide. Such
waveguides may be formed on the same substrate with transistors. These waveguides
may also be electrically biased to alter the index of refraction and/or absorption
of the waveguide.
