Methods and systems for a photonic interposer are disclosed and may include receiving one or more continuous wave (CW) optical signals in a silicon photonic interposer from an external optical source, from an optical source assembly via optical fibers coupled to the silicon photonic interposer. A modulated optical signal may be generated by processing the received CW optical signals based on a first electrical signal received from the electronics die. A second electrical signal may be generated in the silicon photonic interposer based on the generated modulated optical signals, and may then be communicated to the electronics die via copper pillars. Optical signals may be communicated into and/or out of the silicon photonic interposer utilizing grating couplers. The electronics die may comprise one or more of: a processor core, a switch core, memory, or a router.