Photonic integrated circuit for high-wavelength-channel-count wavelength-division-multiplexed systems

An apparatus comprising first photonic-integrated circuit (PIC) comprising a transmitter section disposed on a first substrate, the transmitter section including:

• a plurality of lasers, each laser being a multiwavelength laser configured to produce at least one wavelength comb of a first plurality of wavelength combs, each wavelength comb of the first plurality thereof encompassing a different spectral range and including a plurality of wavelength signals that are separated by a first wavelength spacing, wherein the wavelength combs of the first plurality thereof are separated by a second wavelength spacing that is greater than the first wavelength spacing;
• and
• a star coupler having a plurality of input ports and a plurality of coupler ports;
• wherein the plurality of lasers and the plurality of input ports are optically coupled via a plurality of waveguides such that each input port of the plurality thereof receives a different wavelength comb of the first plurality thereof;
• and
• wherein the star coupler distributes each wavelength comb of the first plurality thereof equally among the plurality of coupler ports to define a plurality of composite output signals, each composite output signal including a substantially equal portion of the optical energy of each of the wavelength signals of each of the first plurality of wavelength combs.