Performance Analysis of CSRZ-OOK With Pairwise or Pulse-to-Pulse Alternate Polarization

The performance of 40-Gb/s carrier-suppressed return-to-zero on-off keying (CSRZ-OOK) combined with either a pairwise or a pulse-to-pulse alternate polarization (APol) is investigated numerically. It is shown that these modulation formats offer a superior suppression of intrachannel four-wave mixing compared to conventional APol-formats. They are also tolerant to narrowband optical filtering and thus suitable for ultradense wavelength-division multiplexing (WDM) systems with a spectral efficiency of 0.8 bit/s/Hz.