Scalability of a metropolitan bidirectional multifiber WDM-ring network

We analyze the scalability of a metropolitan bidirectional multifiber wavel ength-division-multiplexed (WDM) ring network. The analysis is carried out by using a bidirectional transmission model for optical networks and by bui lding an experimental network. The model includes major limiting factors in WDM-ring networks such as relative intensity noise (RIN) due to multiple R ayleigh backscattering, amplified spontaneous emission (ASE) accumulation i n a cascade of bidirectional erbium-doped fiber amplifiers (EDFA), tilting of the EDFA gain spectrum and input saturation power of the EDFA. We found that in metropolitan areas the scalability of a WDM-ring network using bidi rectional transmission is not mainly limited by the RIN arising from the Ra yleigh backscattering. The result was verified experimentally. The maximum size of the demonstrated network is 33-43 nodes with a spacing of 5-10 km b etween nodes. With this spacing, which is typical in metropolitan areas, th e scalability of the network is mainly limited by the gain tilt and the inp ut saturation power of the EDFA.