Abstract

Two methods have been recently proposed to reduce the Gordon-Haus timing jitter of solitons in fibers induced by amplifier noise. One is to modulate pulse trains synchronously in time domain to retime the pulse position by using high-speed optical modulators.¹ The other is to suppress the diffusion of soliton center frequency by using narrow-band filters.^2,3 In the latter method, while having advantages of being passive and being adaptable to wavelength division multiplexing, the problem of linear-wave growth caused by the excess gain around the filter center frequency must be settled. Mollenauer et al. recently demonstrated that sliding the center frequency of the filters along the transmission distance is quite effective to eliminate the accumulation of noise.⁴ Introduction of nonlinear gain which selectively amplifies solitons has also been proposed to suppress the growth of linear waves with small amplitude.^5,6 In this paper, we propose to use nonlinear amplifying loop mirrors (NLM’s)⁷ periodically inserted in the transmission line as a realistic means for high-speed nonlinear-gain elements and present numerical simulation of stable soliton transmission.

© 1994 Optical Society of America