Noise suppression by saturable absorber in transmission systems with semiconductor optical amplifiers

Summary form only given.Semiconductor optical amplifiers (SOA) are a cost-effective solution for high bit-rate communication systems provided that the growth of amplified spontaneous emission (ASE) can be controlled by using e.g., 2R regenerators. A very economic way to distributed regeneration is to fabricate a saturable absorber (SA) layer by ion implantation of one of the SOA chip facets. Such devices have been used in mode-locked lasers and have been shown to be an effective tool for noise suppression in 1.3 /spl mu/m transmission systems with in-line SOA. In this contribution we identify the principal effects which lead to ASE growth suppression, present results on optimization of such system and report an essential performance improvement, especially when a gain clamped SOA has been used.