Patent ID: 6233261
Filing Date: 2001-05-15
Classification: H01S,H04B,H04J

Abstract:
Apparatus for monitoring a plurality of sources of optical radiation, each of the sources producing radiation having a particular wavelength, the apparatus comprising:a wavelength filter composed of a wavelength division demultiplexer (WDM) having an input and two outputs, said filter being connected to receive a portion of the radiation produced by a selected one of the sources and to divide the received radiation into two parts each having a respective power level and each supplied to a respective one of said two filter outputs;two photoreceivers each coupled to a respective one of said two filter outputs for producing signals representing the power levels of the radiation supplied to said two filter outputs; anda processor coupled to said photoreceivers for computing the ratio of the power level of the radiation supplied to one of said filter outputs to the power level of the radiation supplied to the other one of said filter outputs, and for producing a comparison of the computed ratio with a predetermined reference ratio out of a plurality of predetermined reference ratios.