Optical and electrical methods comparison for accurate measurement of erbium-doped fiber amplifiers (EDFA) gain and noise figure

Abstract

At the present time, standards are not yet available to characterize EDFA performances. Several methods have to be tested to provide an accurate and reproducible measurement technique. This paper presents such an investigation for optical and electrical measurement methods. In the first part, the interpolation and polarization nulling optical techniques are presented. The experimental set-up is described in detail. These methods have been applied to measure the gain and the noise figure of EDFA. These measurements have been carried on a commercial EDFA. Meaningful discrepancies have been highlighted. These discrepancies have been analyzed. More especially, the insertion of a narrow band optical filter and the polarization dependence of noise have been investigated. Conclusions have been drawn explaining the measurement results differences. In the second part, the electrical method is detailed and analyzed. The influence of the laser RIN on the noise figure measurement is put into light. The signal spontaneous noise becomes a major contribution and care has to be taken to avoid it. Optical filtering of the signal is then highly recommended. Finally both electrical and optical methods are compared. The errors originating from respective methods are highlighted.