Comparison of 8 x 112 Gb/s PS-QPSK and PDM-QPSK signals over transoceanic distances

We experimentally investigate polarization-switched quadrature phase-shift keying (PS-QPSK) with a symbol rate of 37.3 GBd corresponding to a bit rate of 112 Gb/s. In a wavelength-division multiplexing (WDM) experiment with 50 GHz channel spacing, the transmission performance of PS-QPSK is compared to that of polarization-division multiplexed QPSK (PDM-QPSK) over an EDFA amplified ultra-large-effective-area fiber link. For a bit-error ratio (BER) of 3.8 x 10(-3), the achieved transmission distance is 11000 km for PS-QSPK and 10000 km for PDM-QPSK.