Monolithic integration of optical waveguides with metal routing layers

A photonic integrated circuit comprising:

• a lower metal layer;
• an intermetal dielectric level on the lower metal layer;
• an upper metal layer on the intermetal dielectric level;
• one or more optical waveguide levels within the intermetal dielectric level, each optical waveguide level including one or more optical waveguides formed therein, each of the one or more optical waveguide levels having corresponding top and bottom faces;
• one or more optical gratings, each of the one or more optical gratings formed in a corresponding one of the one or more optical waveguide levels, each of the one or more optical gratings adapted to out-couple light;
• and
• one or more metal vias in the intermetal dielectric level, each of the one or more optical waveguides formed in each of the one or more optical waveguide levels laterally separated from each of the one or more metal vias by a distance D4, each of the one or more metal vias includes one or more encircling optical baffles, each of the one or more encircling optical baffles including a corresponding wall forming a “U” shape that at least partially encircles a corresponding one of the one or more optical gratings, each corresponding wall of each of the one or more encircling optical baffles being substantially perpendicular to a plane of the intermetal dielectric level, each of the one or more encircling optical baffles adapted to block stray light;
• wherein:
• a top face of an uppermost optical waveguide level of the one or more optical waveguide levels is a distance D1 from the upper metal layer;
• a bottom face of a lowermost optical waveguide level of the one or more optical waveguide levels is a distance D2 from the lower metal layer;
• and
• D1 and D2 are both at least 600 nm but not more than 1200 nm.