tools and methods for making molded an optical integrated circuit including one or more waveguides are disclosed . in one embodiment , a molding die is provided that includes a substrate that has a topographically patterned first surface . a conformal protective film is provided over the first surface of the substrate . the substrate may be formed of silicon or gallium arsenide , and may be patterned using conventional semiconductor patterning techniques , such as plasma etching . the protective film may be metal , diamond , or some other hard material . typically , a plurality of such molding dies are formed from a wafer of the substrate material . the die is pressed into a moldable material , such as thermal plastic , to form the wave guide of the optical integrated circuit . a plurality of the dies may be mounted around the curved surface of a heated roller , and a heated tape of the waveguide material may be fed under the roller in a mass production process . alternatively , the die may be mounted in an injection molding cavity , and the ioc may be formed by an injection molding process .