The Availability Analysis of Many WDM Channels Through a Cascade of EDFAs without Gain Equalization

Abstract

Erbium-doped Fiber Amplifiers(EDFAs) are revolutionizing both long-distance and distribution based optical communication systems^1,2, since they compensating for fiber attenuation and network splitting losses, respectively. Furthermore, optically-amplified systems can have a manifold increasing in the total capacity by incorporating wavelength-division-multiplexing(WDM). However, one key difficulty in implementing a WDM system incorporating EDFAs is that the gain spectrum is wavelength dependent. This will result in a severe signal-to-noise ratio differential among channels after passing through a cascade of EDFAs. Moreover, a wide band WDM system cannot accommodate a narrow optical filter along the propagation path to attenuate the unwanted amplified spontaneous emission (ASE) noise. This wide band ASE contributes to saturating subsequent amplifiers in the cascade thereby reducing the gain available to the signal.