Polarization bit interleaving of return-to-zero (RZ) pulses doubles spectral efficiency with reduced pulse-to-pulse interaction. We report transmission of sixteen 25-Gbit/s polarization-bit-interleaved RZ differential binary phase-shift-keyed (DBPSK) dense-WDM (DWDM) signals with 25-GHz channel spacing over 400 km of SMF-28 fiber link. The EDFA-based link has an amplifier spacing of 100 km with an average loss of 25 dB between erbium-doped fiber amplifiers (EDFAs) and a maximum span loss of up to 30 dB. A transmission penalty of 1.5 dB after 400 km was obtained. Compared with one polarization, a net penalty of 0.6 dB after 400 km was obtained. To the best of our knowledge, this is the first transmission test of multichannel polarization-bit-interleaved RZ-DBPSK signals operating at 25 Gbit/s with a spectral efficiency of 0.8 bit/s/Hz.
© 2003 Optical Society of AmericaPDF Article