Multichannel amplification utilizing an Er3+-doped fiber amplifier

An Er³⁺-doped fiber amplifier for multichannel systems was studied from the viewpoint of clarifying the ultimate capacity of the applicable number of channels. In these experiments, 10-GHz spaced 100-channel common amplification was carried out in a 622-Mb/s frequency-shift-keying (FSK) direct detection scheme, together with measurement of the amplifier characteristics. Bit-error-rate measurements show that the power-penalty characteristics for 100-channel amplification are the same as for one-channel amplification. Based on the experimental results, possible channel capacity is discussed. There are two possible factors limiting channel capacity in multichannel amplification of fiber amplifiers: signal-gain bandwidth and amplifier noise. Calculations using the amplifier parameters obtained during the experiments reveal that signal gain bandwidth is the main factor limiting channel capacity in the amplifier used