Unimpaired transmission through a bidirectional erbium-doped fiber amplifier near lasing threshold

Abstract

We present transmission experiments with an erbium doped fiber amplifier (EDFA) without optical isolators, designed for bidirectional transmission. The combination of high gain and reflections/Rayleigh backscattering may result in laser action of the EDFA at the maximum-gain wavelength 1531 nm. It was demonstrated that wavelength-selective transmission at 1537 nm was unimpaired for G/sub 1531//sup 2/R/sub 1/R/sub 2//spl les/-15 dB. The gain saturation due to laser action and the multiple-reflection penalty were both less than 0.5 dB. A specification for the allowable maximum gain of a bidirectional EDFA is derived.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>