Very-Low Threshold Loop-Mirror Switch Incorporating an EDFA

Abstract

All-optical switching devices based on ultra-fast optical non-linearities are of considerable interest for use in high-speed optical signal processing and telecommunications systems. Several switching schemes utilising χ(3) in optical fibres1-4 have been reported, but, although fast, they have large switching thresholds (100 -1000W) and suffer from environmental instability. Recent work5-7 has concentrated on the fibre Non Linear Optical Loop Mirror (NOLM) (or non-linear Sagnac interferometer), since the configuration is inherently a balanced interferometer and therefore environmentally stable. Consequently, longer fibre lengths can be used and the switching threshold reduced to 10-100W, a figure which is unfortunately still too high for practical application.