Abstract

For long-distance data communication based on coherent optical transmission in single-mode optical fibres, the use of soliton pulses as information carriers has raised a large interest since the NLS soliton concept (solution of the nonlinear Schrodinger equation) in dispersive optical fibres by Hasegawa and Tappert [1] and its first experimental verification by Mollenauer et al. [2]. High bit rate transmission capacity may be achieved by this technique if the minimum distance between solitons (5 to 10 times their width) avoids the interaction between them [3]. Recent experiments have demonstrated: (i) soliton transmission over more than 4000 km in a nonshifted-dispersion single-mode fibre (hereafter called n.d.-s.f.) in which losses are periodically compensated by Raman gain [4], and over 9000 km in a dispersion-shifted fibre [5] (hereafter called d.-s.f.); (ii) generation and transmission of high-bit rate optical solitons (up to a repetition rate fbit = 20 GHz) in dispersion-shifted fibres, losses being compensated by amplification in an Er³⁺ - doped fibre, using a color-center laser [6(a)], or a directly modulated distributed-feedback laser diode [6(b)].

© 1991 Optical Society of America