Abstract: Apparatus for simultaneously monitoring and controlling the wavelength of a plurality of semiconductor lasers whose wavelengths can be adjusted, the device including a wavelength filter including a wavelength division demultiplexer (WDM) arranged to receive a portion of the output power of each laser and divide the laser output between two filter outputs, a photoreceiver arranged to measure the power at each filter output, a processor arranged to selectably compute the ratio of the power at the two filter outputs for each laser, apparatus to compare the computed ratio with a predetermined reference ratio for the selected laser, and apparatus to adjust the wavelength of the selected laser in response to the comparison.

Abstract: A device and method for monitoring and controlling the wavelength of a semiconductor laser having an adjustable wavelength, the device including a wavelength filter including a medium-dense wavelength division demultiplexer (WDM) arranged to receive a portion of the laser power of the laser and divide it between two filter outputs, a photoreceiver arranged to measure the output power at each filter output, a processor coupled to the photoreceivers and arranged to compute the ratio of power at the two filter outputs, apparatus to compare the computed ratio with a predetermined reference ratio, and apparatus to adjust the wavelength of the laser in response to the comparison.