Joint-polarization carrier phase estimation for PS-QPSK signals

We investigate a carrier phase estimation algorithm for the polarization-switched quadrature phase-shift-keying modulation format. The algorithm, which is based on the conventional block Mth power feed-forward scheme, works jointly on both polarizations and shows a significant performance improvement compared with a polarization-independent scheme. We evaluate the tolerance to laser phase noise in numerical simulations and the tolerance to nonlinear distortions in single-channel and Nyquist wavelength-division-multiplexing transmission experiments over up to 17 000 km of ultralarge-effective-area fiber.