Characteristics Evaluation of Multi-Stage Optical Amplifier EDFA

In optical fiber communication systems, the non-perfectly transparent material of the fiber causes the visible-light or infrared beams to be attenuated as they travel through it. This necessitates the use of optical amplifier in order to remedy this signal attenuation. In this regard, the fiber amplifier is a key enabling technology for high speed optical communications. The EDFA is a successful optical amplifier that represents a significant factor in the rapid deployment of optical fiber networks. It uses proven erbium-doped fiber (EDF) technology to allow amplification of an optical signal without the need of costly regenerative repeater stations. Its large gain bandwidth, which allows simultaneous amplification of a numerous number of channels at different wavelengths within the spectrum of nearly constant gain, is very attractive in many practical applications. This property is very useful in WDM which is widely used in optical fiber data links owing to its dominant role that it plays in the next generation of high speed networks. Additionally, it may be positioned as a booster, pre-amp or in-line position to allow the amplification of the signal along any point of the optical network. Moreover, it can efficiently amplify light in the 1.5 μm wavelength region, where telecom fibers have their minimum loss.

This paper is intended to the evaluation of multi-stage EDFA performance for different EDF lengths, the two commonly used pumping wavelengths (980 nm & 1480 nm), and the distinct configurations of pumping mechanism. The gain and noise characteristics of different number of stages are computed and compared through simulation. Our attention is specially paid towards the optimum values of the system parameters that will give highest gain and lowest noise figure as well as minimum bit error rate in order to achieve the longest propagation length without signal degradation.