Nonlinear gain control of dispersion-managed soliton amplitude and collisions

The stabilizing action of nonlinear gain on dispersion-managed soliton tran smissions is investigated. By means of a proper combination of nonlinear ga in and filtering, the background and amplitude instability introduced by lu mped guiding filters can be controlled. Indeed, radiative background that m ay not be separated from the signal when the average dispersion is close to zero is shown to be suppressed. Taking advantage of the large tolerance wi th respect to input energy variations, dispersion-managed solitons are foun d to be stable after collisions among different frequencies when supported by the same nonlinear gain element for all channels. This demonstrates the feasibility of nonlinear gain for wavelength-division-multiplexed transmiss ions and may open up the possibility of high-speed soliton transmission wit h large tolerance with respect to power fluctuations and densely packed wav elength channels. (C) 2000 Academic Press.