A method for making an integrated circuit may include forming at least one
active optical device and a waveguide coupled thereto. The waveguide may
include a superlattice including a plurality of stacked groups of layers.
Each group of layers of the superlattice may include a plurality of
stacked base semiconductor monolayers defining a base semiconductor
portion and an energy band-modifying layer thereon. The energy-band
modifying layer may include at least one non-semiconductor monolayer
constrained within a crystal lattice of adjacent base semiconductor
portions.