Patent ID: 8155488

Claim:
A photonic integrated circuit comprising: a substrate; and a plurality of signal channels provided on the substrate, each of the plurality of signal channels comprising: a laser source providing a corresponding one of a plurality of optical outputs at a respective one of a plurality of emission wavelengths, and an external modulator configured to receive the corresponding one of the plurality of optical outputs and modulate data on the corresponding one of the plurality of optical outputs, the external modulator further configured to superimpose a respective one of a plurality of tones on the corresponding one of the plurality of optical outputs to provide a corresponding one of a plurality of modulated optical outputs; a circuit configured to determine a respective one of the plurality of emission wavelengths and a corresponding one of a plurality of power values associated with each of the plurality of signal channels from the plurality of tones; and an optical combiner having a plurality of inputs and an output, wherein each of the plurality of signal channels comprises a photodiode configured to receive the corresponding one of the plurality of modulated optical outputs and attenuate the corresponding one of the plurality of modulated optical outputs to provide a corresponding one of a plurality of attenuated optical signals, each of the plurality of inputs of the combiner configured to receive a respective one of the plurality of attenuated optical signals, the combiner combining the plurality of attenuated optical signals into a WDM signal provided at the output of the combiner.