Bidirectional transmission at 622 Mb/s utilizing erbium-doped fiber amplifiers

Abstract
Amplification of two bidirectional 622-Mb/s optical signals was demonstrated using a single erbium-doped fiber amplifier (EDFA). Bidirectional amplification was examined with the EDFA operating as a midspan repeater and as a pre/post amplifier at one terminal end of a 95-km fiber span. Without using any isolators in the EDFA, bidirectional optical amplification through a single EDFA was achieved while simultaneously improving system gain relative to a unidirectional link without an EDFA. The system gain improvement was 9.5 and 7 dB in the pre/post configuration, and 25.5 and 20.3 dB in the midspan configuration, when the signal wavelengths were 1537 and 1545 nm, respectively.<>