A silicon interposer. The silicon interposer including: a silicon layer, including one or more optical waveguides each connectable to an optical fiber; an optically active component, configured to convert optical signals received from the optical fiber into electrical signals or to convert electrical signals into optical signals and provide them to the optical fiber; and one or more electrical interconnects, connected to the optically active component and connectable to a printed circuit board, a separate die, a separate substrate, or a wafer level package.