Estimated performance of 2.488 Gb/s CPFSK optical non-repeatered transmission system employing high-output power EDFA boosters

The configuration of a practical nonrepeatered coherent optical transmission system and its performance are reported. The practicability of combining continuous-phase frequency-shift keying (CPFSK) with erbium-doped fiber amplifier (EDFA) boosters is verified by laboratory and field experiments. A system gain of 60.8 dB is achieved at a BER at 10^-11; the EDFA´s optical output power is +18 dBm and the receiver sensitivity is -42.8 dBm. The stimulated Brillouin scattering (SBS) effect is examined to estimate the dependence of error rate characteristics on the bit sequence length. No power penalty is observed for a pseudorandom bit sequence (PRBS) of more than 2⁵-1 or STM-16 patterns containing a 30-byte block of consecutive identical digits. The power penalty of 1.3 dB caused by the 310-km non-dispersion-shifted transmission fiber is successfully compensated by installing a chromatic dispersion compensator in each orthogonal polarization branch. During a four month field experiment, error-free operation was observed over a 30 day period, and the long-term error rate is under 6×10^-16