1.14 b/s/Hz spectrally efficient 50 x 85.4-Gb/s copolarized return-to-zero differential quaternary phase-shift keying (RZ-DQPSK) signals have been transmitted over 300 km of nonzero dispersion-shifted fiber (NZ-DSF), using optical prefiltering and conventional C-band erbium-doped fiber amplifier (EDFA) repeaters. In this study, in order to enhance the spectral efficiency,the impact of optical prefiltering on the RZ-DQPSK signal was experimentally investigated in comparison to the DQPSK signal, and we found that the RZ-DQPSK signal had better sensitivity with almost the same nonlinear tolerance than the DQPSK signal even with 65-GHz bandwidth optical prefiltering.
© 2005 IEEE
Noboru Yoshikane and Itsuro Morita, "1.14 b/s/Hz Spectrally Efficient 50 x 85.4-Gb/s Transmission Over 300 km Using Copolarized RZ-DQPSK Signals," J. Lightwave Technol. 23, 108- (2005)