Practical implementation of a highly sensitive receiver using an erbium-doped fiber preamplifier

A practical erbium-doped fiber preamplified direct detection receiver is demonstrated with which receiver input sensitivities of -46.5 dBm at 622 Mb/s and -40.7 dBm at 2.3 Gb/s have been achieved. There is no penalty from the transmission fiber Rayleigh backscattering. The bit error ratio measurements with 2/sup 23/-1 NRZ PRBS (pseudorandom bit sequence) show highly stable characteristics with no apparent error floor, owing to the polarization insensitivity of the preamplifier and to an active locking of the receiver optical filter. The tradeoff between preamplifier and avalanche gain is shown, and the influence of optical filter bandwidth and decision threshold setting is measured.<>