Linewidth-tolerant and low-complexity two-stage carrier phase estimation using QPSK constellation transformation for 112 Gb/s PM 16-QAM systems

The performance of QPSK constellation transformation based two-stage carrier phase estimation algorithms is assessed for 16-ary quadrature-amplitude-modulation. Experimentally the linewidth tolerance of the algorithms is shown to be comparable to the blind phase search algorithm, but with a reduction in the hardware complexity by factors of about 3-8.