Patent ID: 8326155

Claim:
An optical demultiplexer for separating wavelength division multiplex (WDM) optical radiation having a plurality of wavelength channels spaced over a wavelength spectrum into individual wavelength channels, the optical demultiplexer comprising: a first demultiplexer configured to divide WDM optical radiation into a plurality of sub-bands, each sub-band comprising a plurality of adjacent wavelength channels and being emitted at a respective first demultiplexer output; one or more demultiplexer arrangements configured to separate each sub-band into individual wavelength channels, each individual wavelength channel being emitted at a respective demultiplexer arrangement output, and each demultiplexer arrangement comprising: an optical amplifier configured to optically amplify all the adjacent wavelength channels in a sub-band; a demultiplexer configured to separate each of the adjacent wavelength channels into the individual wavelength channels such that each individual wavelength channel is emitted at a respective demultiplexer arrangement output; a power monitor configured to measure the power of each individual wavelength channel at its respective demultiplexer arrangement output; and a controller configured to control the optical amplifier based on the measured power of the individual wavelength channels such that the power of each individual wavelength channel remains substantially at a predetermined power level.