An Integrated Optical Spectral Polarimeter for Signal Monitoring and Feedback to PMD Compensators

An integrated high-resolution spectral polarimeter is demonstrated in 4%-index-contrast Ge-doped silica waveguides. A ring resonator achieves a wavelength selectivity of less than 2 GHz FWHM, and tunability is realized via thermo-optic phase shifters with scanning speeds on the millisecond timescale. Real-time, in-service PMD monitoring is thus enabled for studying dynamic channel behavior and for feedback to adative compensators. Measurements of DGD, output state of polarization, and PSPs are presented on 10 and 40 Gb/s modulated signals. Measurements on time-varying PMD and higher-order PMD are also presented to demonstrate the device's capability.