A computer program product or hardware description language (“HDL”) design structure in a computer-aided design system for generating a functional design model of an integrated circuitry structure including generating a functional representation of at least first and second regions of the integrated circuitry structure, generating a functional representation of an optical layer comprising optical waveguides, and generating a functional representation of a heat-conductive material for transferring heat from at least the second region through the optical layer to a heat sink.