MODELING, MEASUREMENT, AND A SIMPLE ANALYTIC APPROXIMATION FOR THE RETURN LOSS OF ERBIUM-DOPED FIBER AMPLIFIERS

When fiber-optic systems contain erbium-doped fiber amplifiers (EDFA), reflections are enhanced by the gain of the amplifiers and can degrad e system performance, We present a simple approximate analytic express ion for the return loss of pumped EDFA's, with and without discrete re flections that applies at both the signal and pump wavelengths, A nove l return loss measurement test set is used to verify the validity of t his expression for a particular EDFA design, Using a computer simulati on, the return loss is computed as a function of EDFA design to assess the range of validity of the approximate expression. The expression s erves as an easy way to chain amplifiers and accurately predict the ef fects of reflections in long systems.