Silicon waveguide structure with arbitrary geometry on bulk silicon substrate, related systems and program products

A silicon-based optical waveguide structure comprising:

• a bulk silicon substrate;
• a set of waveguide structures positioned within the bulk silicon substrate, wherein each of the set of waveguide structures includes:
• a silicon dioxide (SiO2) layer filling a cavity within the bulk silicon substrate;
• an intermediate layer directly over the SiO2 layer, the intermediate layer having a substantially flat lower surface contacting the SiO2 layer;
• and
• a silicon layer overlying the intermediate layer,
• wherein the SiO2 layer extends above the intermediate layer through the silicon layer,
• wherein the set of waveguide structures includes a plurality of waveguide structures, wherein one of the plurality of waveguide structures includes a non-uniform thickness region in the silicon layer overlying the intermediate layer,
• wherein a second one of the plurality of waveguide structures does not include a non-uniform thickness region in the silicon layer overlying the intermediate layer.