Abstract

In long distance optical amplifier systems, polarization-dependent gain (PDG) and polarization-dependent loss (PDL) in repeaters cause fluctuation and reduction of Q factor [1]-[6]. PDG is caused by polarization hole burning (PHB) in the Erbium-doped fiber amplifiers (EDFAs) [7][8] and PDL by passive devices, such as optical isolators and couplers. Recently, it has been reported that the polarization scrambling with frequency of several hundred kHz reduced the Q degradation due to PDG in 5 Gb/s system [9]. Moreover, it was found that the Q degradation due to PDL as well as PDG can be suppressed using the high speed scrambling with frequency higher than the bit rate in 622 Mb/s system [10]. However, the high speed polarization scrambler would not be easy to realize for the multi-Gb/s systems.

© 1994 Optical Society of America