Methods and systems for monolithic integration of photonics and electronics in CMOS processes are disclosed and may include in an optoelectronic transceiver comprising photonic and electronic devices from two complementary metal-oxide semiconductor (CMOS) die with different silicon layer thicknesses for the photonic and electronic devices, the CMOS die bonded together by metal contacts: communicating optical signals and electronic signals to and from said optoelectronic transceiver utilizing a received continuous wave optical signal as a source signal. A first of the CMOS die includes the photonic devices and a second includes the electronic devices. Electrical signals may be communicated between electrical devices to the optical devices utilizing through-silicon vias coupled to the metal contacts. The metal contacts may include back-end metals from a CMOS process. The electronic and photonic devices may be fabricated on SOI wafers, with the SOI wafers being diced to form the CMOS die.