An optoelectronic substrate comprises an electronic device, an optical device, and an optical wiring layer, the optical wiring layer comprising a photonic crystal. An optoelectronic substrate comprises an electronic device, an optical device, and an optical wiring layer, wherein the optical wiring layer is comprised of a periodic structure having a repeating period nearly equal to or smaller than the wavelength of light employed for signal transmission. An optoelectronic substrate comprises an electronic device, an optical device, an electric wiring connected to the electronic device, an optical wiring layer, and a base plate, wherein the optical wiring layer is employed as an insulating layer between the base plate and the electric wiring.