Patent ID: 8494369

Claim:
An optical device, comprising: a substrate; an optical demultiplexer provided on the substrate, the optical demultiplexer including a demultiplexer input and a plurality of demultiplexer outputs, the demultiplexer input being configured to receive, as a first WDM signal, a plurality of input optical channels, each of the plurality of input channels having a corresponding one of a plurality of wavelengths and being separated from one another by a first wavelength spacing, a first one of the plurality of demultiplexer outputs supplying a first plurality of output optical channels as a second WDM signal, each of the first plurality of output optical channels being separated from one another by a second wavelength spacing, and a second one of the plurality of demultiplexer outputs supplying a second plurality of output optical channels as a third WDM signal, each of the second plurality of output optical channels being separated from one another by the second wavelength spacing, the second wavelength spacing being greater than the first wavelength spacing; a first output waveguide provided on the substrate, the first output waveguide being coupled to the first one of the plurality of demultiplexer outputs to receive a first portion of the second WDM signal; and a second output waveguide provided on the substrate, the second output waveguide being coupled to the first one of the plurality of demultiplexer outputs to receive a second portion of the second WDM signal, the second output waveguide being configured to supply the second portion of the second WDM signal; and a photodiode configured to receive the second portion of the second WDM signal from the second output waveguide, wherein the plurality of input optical channels are a plurality of first input optical channels, the optical device further comprising: an optical multiplexer provided on the substrate, the optical multiplexer having a plurality of multiplexer inputs, each of which being configured to receive a corresponding one of a plurality of groups of second input channels; collectively, said plurality of groups of second inputs channels constituting a fourth WDM signal, the optical multiplexer also having a multiplexer output configured to supply the fourth WDM signal.