Patent ID: 7437029

Claim:
A method of manufacturing a monolithic transmitter photonic integrated circuit (TxPIC) comprising: forming an integrated array of modulated sources on a common substrate to provide a plurality of respective channel signals of different wavelengths, the active layer of the modulated sources comprising multiple quantum wells (MQWs); forming either above or below and in proximity to the active layer a grating layer where the grating period of each of the modulated sources is set to provide one of the different wavelengths; etching back through the active layer in a region of the circuit where an integrated optical combiner is to be formed to receive the channel signals from the modulated sources and produce a combined WDM signal output of the channel signals; and forming through epitaxial regrowth a waveguide core layer for the optical combiner in the etched back region that is butt coupled directly to the MQW layer to receive the respective channel signals from the modulated sources, the waveguide core layer comprising a single bulk layer.