Abstract

The sliding frequency filter has, by suppressing the Gordon-Haus arrival time jitter and the amplitude noise in both the “1”s and the “0”s, made possible soliton transmission over significantly longer distances and at higher bit rates. Higher bit rates are achieved by decreasing the soliton width. Since σ_G-H can be kept small the detection window needed for a BER of 10^-9 is significantly less than the soliton soliton spacing of 5 τ. One would like to decrease the soliton spacing in order to further increase the bit rate. The limit on the soliton spacing will now be determined by the strength of the soliton soliton interaction. Using numerical simulation, we have studied how the sliding filters modify the solitons-soliton interaction. Simulations with copolarized solitons τ = 20 ps., η= 0.6 (filter curvature) and a sliding rate of +1.4 GHz/z_c a soliton spacing of 3 τ show the interaction is completely suppressed over a distance of at least 12,000 km. This translates to a 60% increase in the bit rate. For many reasons it is attractiave to do polarization multiplexing of solitons. We have studied the interaction of orthogonally polarized solitons in a fiber with polarization mode dispersion (PMD) and sliding frequency guiding filters. Here the nearest neighbor interaction for solitons, spaced closer than ~3 τ, is modified by the time delay induced by the fiber birefringence. This can have a profound effect, depending on the amount of PMD, on the basic interaction. We will show the effect the sliding filter has on suppressing the soliton soliton interaction for orthogonally polarized solitons.

© 1993 Optical Society of America