Methods and systems for a chip-on-wafer-on-substrate assembly are disclosed and may include in an integrated optical communication system comprising an electronics die and a substrate. The electronics die is bonded to a first surface of a photonic interposer and the substrate is coupled to a second surface of the photonic interposer opposite to the first surface. An optical fiber and a light source assembly are coupled to the second surface of the interposer in one or more cavities formed in the substrate. The integrated optical communication system is operable to receive a continuous wave (CW) optical signal in the photonic interposer from the light source assembly; and communicate a modulated optical signal to the optical fiber from said photonic interposer. A mold compound may be on the first surface of the interposer and in contact with the electronics die. The received CW optical signal may be coupled to an optical waveguide in the photonic interposer using a grating coupler.