Abstract

Continuous, dispersion varying fibres (DVFs) offer a wide range of potential applications for distributed linear/nonlinear pulse manipulation and control. With the development of simple fibre fabrication technology capable of manufacturing up to 40 km lengths of DVF considerable attention has focussed on their potential application as a transmission media in advanced soliton communication systems. As pointed out by Tajima [1] fibres with exponentially varying dispersion matched to follow the fibre loss can be used to eliminate the deleterious effects of the local imbalances in nonlinearity and dispersion that arise as a result of the pulse energy variation between amplifier spans in a conventional soliton transmission line. These localised imbalances restrict the bit-rates that can be used in single channel systems once the soliton period of the pulses approaches that of the amplifier spacing, and also give rise to serious inter-channel effects in soliton WDM systems [5]. Single pulse transmission experiments have recently been demonstrated illustrating loss compensation over single amplifiers spans using loss compensating dispersion decreasing fibre (LCDDF)[2,3]. These early results have been followed by multi amplifier-stage experiments, illustrating application to the periodically amplified case for short pulses in regimes not permitted by conventional average soliton dynamics [4]. However, error free pulse transmission for high bit-rate single channel data transmission was found to be limited by effects such as the soliton acoustic interaction and Gordon Haus jitter which are pronounced due to the high path average path dispersion of the available LCDDFs [4]. In order to obtain significantly better results, LCDDFs with correspondingly smaller absolute dispersion range variations need to be developed. (Note that the application of a discrete approximation to the desired exponential dispersion profile for enhanced soliton WDM transmission have also been demonstrated [5]). In this paper we present initial results on the development of low dispersion, LCDDFs and present the first experimental results on the use of these more gently tapered fibres in recirculating loop experiments. We show that the lower average dispersion reduces the strong deleterious effects observed in the earlier loop experiments and obtain error free, 10 GBit/s, 4.7ps pulse transmission over fibre lengths in excess of 4300km.

© 1996 Optical Society of America