Determination of ratios signal / noise optical band optical signals polarization states of variables over time using polarization extinction

摘要

A method for measuring the signal / optical noise of an optical signal containing a plurality of channels wavelength variable states polarization over time, comprising: (a) filtering the optical signal to form a test signal comprising one of the channels of wavelength or optical frequency selected one of the channels selected wavelength; (B) transforming the polarization state of the test signal in a pseudo random sequence or of different polarization states transformed; (C) filtering a first polarization state of the polarization states of the processed test signal with a polarization filter (26) under a predetermined fixed orientation; (D) measuring the optical power of the test signal transmitted through the polarization filter (26) in each of the polarization states processed in order to determine a power of optical signal maximum and minimum measures; and (e) calculating a polarization extinction ratio from measurements of the signals received maximum and minimum in order to obtain a signal / noise ratio for the optical test signal ratio; where the measurement time of step (d) is sufficiently short so that the polarization state of the optical light signal on the channel selected wavelength is substantially constant during measurement of the optical power, thus limiting degradation in polarization extinction ratio of calculated, wherein in step (b) comprises: (i) random or pseudo modulate the polarization state of the test signal to a first scheme; and (ii) transforming the polarization state of the modulated test signal or pseudo random sequence of different polarization states to a second slower rate than the first regime