Abstract

Spontaneous emission from amplifiers perturbs the amplitudes and widths of solitons in ultralong distance transmission. These perturbations alter the rate of self-frequency shift (intrapulse Raman scattering) of the solitons, in turn changing the rate of inverse group velocity shift per unit distance, through group velocity dispersion. This results in a spread in the arrival times at the receiver. Although these deceleration shifts are weak for pulses >1 ps wide, they can be significant when integrated (twice) over ultralong distances. We find, for reasonable parameter values, that the timing jitter from this effect, and thus the propagation distance limit, exceeds that of the Gordon-Haus limit¹ at bit rates as low as a few tens of Gbit/s. Such bit rates might be achievable if all-optical pulse restoration elements² are introduced into long distance communications systems. With such elements, the distance limitations imposed by timing jitter no longer apply to the entire system length but rather to the distance between pulse restoration elements, and this increases the achievable bit rate-system length product.

© 1991 Optical Society of America