Abstract

The transmission performance of long-haul optical amplifier transmission systems can be impaired by added accumulated noise caused by polarization hole-burning^1,2 in the erbium- doped fiber amplifiers. Scrambling the state-of-polarization of the launched optical signal to depolarize the optical carrier can improve the received signal-to-noise by reducing polarization hole-burning.^3,4 We find that the optimal choice of the scrambling frequency is the clock frequency that defines the bit rate of the transmitter. This technique is particularly important for the efficient use of optical bandwidth in wavelength-division multiplexed (WDM) systems. In addition, synchronous polarization scrambling with superimposed phase modulation (PM) can dramatically increase the eye opening of the received data pattern. The increase in eye opening results from the conversion of PM into bit-synchronous amplitude modulation through chromatic dispersion and nonlinear effects in the fiber. This new technique of synchronous polarization/phase scrambling has allowed us to demonstrate a total transmission capacity of 100 Gbit/s (20 WDM channels at 5 Gbit/s) over 6300 km.⁵

© 1996 Optical Society of America