Repeated bidirectional transmission using two 4-port optical circulators and a bidirectional EDFA without isolators

By using a newly designed bidirectional erbium-doped fiber amplifier, we de monstrated a 2 x 2.5 Gb/s repeated bidirectional transmission over a 100-km single-mode fiber. Two tunable optical bandpass filters were used to suppr ess the Rayleigh backscattering and amplified spontaneous emission in the b idirectional transmission system. The bit error rate performances were meas ured for both directions. A negligible power penalty of 0.2 dB for the 2 x 2.5 Gb/s transmission due to backreflections was observed when comparing th e bidirectional transmission with single-channel, unidirectional transmissi on. (C) 1999 Academic Press.