Abstract

Optical solitons are expected to play a key role in single-mode optical-fiber communication systems. However, they are still degraded by the linear fiber loss. Therefore, in order to be realistically feasible, soliton-based systems will need repeaters to enhance the signal, and, from a practical point of view, optical amplifiers are preferable to electro-optical ones. The use of Raman nonlinearity,¹ and, more recently, the use of rare-earth-doped fibers,² have been proposed for such optical amplification. We have numerically simulated pulse propagation through singlemode silica fibers doped with passive two-level atoms in an attempt to cancel the linear fiber loss by the well known doping resonant nonlinearities. Our first results, from experiments carried out in a variety of circum-stances, indicate that the linear rate of loss may be diminished with a proper choice of parameters but that the doped fiber by itself is unable to support steady propagation.

© 1990 Optical Society of America