Spectral Power Fluctuations in DWDM Networks Caused by Spectral-Hole Burning and Stimulated Raman Scattering

Publisher Summary In the 1990s, spectral hole burning (SHB) in the gain spectrum of erbium-doped fiber amplifier (EDFA) was identified as a small higher order effect with magnitude of only a fraction of a dB. Likewise, the manifestation of stimulated Raman scattering (SRS) of dense wavelength division multiplexing (DWDM) channels in the transmission fiber was estimated to cause a small power transfer from short wavelength channels to the longer ones, both at the bit level and on average power basis. Even these small effects can cause significant impairment of channels in the modern wavelength division multiplexing networks, which consist of 100 or more channels covering most of the EDFA gain spectrum and transmission reach requiring concatenation of tens to hundreds of amplifiers, particularly when the channel loading in the network is changed. It therefore becomes an imperative for the system designers to quantify the system impact and then develop strategies to mitigate or manage the adverse impact of these effects. This chapter provides the physics of these effects. It also provides an assessment of the system impact of SHB and SRS through experimental investigation of gain-controlled amplifiers in a circulating loop. It describes the impact of these effects based on treating the amplifier as a black box.