In-Band DGD Monitoring Based on Polarization Controlled Stimulated Brillouin Scattering

In this letter, we present a new all-optical method for the measurement of the wavelength-resolved state-of-polarization vector across the bandwidth of multiple in-service channels. Taking advantage of the narrow spectral selectivity of stimulated Brillouin scattering and its dependence with the relative polarization alignment between the pump and the stimulus, polarization selective spectral measurements are performed on the signal under test. Obtaining the spectra for three pairs of orthogonal polarization states of the pump, the three Stokes parameters are retrieved for each spectral component. Differential group delay is then calculated from the spectral evolution of the polarization state.