Optical signal monitoring method and apparatus

摘要

A method of monitoring a differential group delay (DGD) of an optical communications signal having a polarisation multiplexed modulation format is described. The method includes the operations of receiving a signal and performing analogue to digital conversion of the signal to generate a digitised signal corresponding to one polarisation of the signal and to generate another digitised signal corresponding to another polarisation of the signal, and applying a polarisation mode dispersion(PMD) compensation to each of the digitised signals. The method further includes the operations of obtaining an indication of the channel transfer function of the optical communications signal, determining a DGD in dependence on the indication of the channel transfer function, determining a delay between the PMD compensated digitised signals, subtracting the delay from the DGD to obtain a corrected DGD, and generating and transmitting a monitoring signal with an indication of the corrected DGD.

主权项

1. A method of monitoring a differential group delay of an optical communications signal having a polarisation multiplexed modulation format, the method comprising:
receiving the optical communications signal in an optical receiver and performing analogue to digital conversion of the optical communications signal to generate a first digitised signal corresponding to a first polarisation of the optical communications signal and to generate a second digitised signal corresponding to a second polarisation of the optical communications signal; applying a polarisation mode dispersion compensation to each of the digitised signals; obtaining an indication of the channel transfer function of the optical communications signal; determining the differential group delay in dependence on the indication of the channel transfer function; determining a delay between a polarisation mode dispersion compensated first digitised signal and a polarisation mode dispersion compensated second digitised signal; subtracting the delay from the differential group delay to obtain a corrected differential group delay; and generating and transmitting a monitoring signal comprising an indication of the corrected differential group delay.