A novel repeaterless CPFSK coherent lightwave system employing an optical booster amplifier

A novel system configuration for repeaterless transmission in conjunction with optical booster amplifiers is proposed. A nonlinear propagation section is introduced in the transmission fiber for the suppression of stimulated Brillouin scattering (SBS) and Raman amplification. The basic characteristics of the nonlinear propagation section were clarified experimentally. It was confirmed that the modulation index of the continuous-phase frequency shift keying (CPFSK) scheme can be selected without SBS restriction. A transmission experiment was conducted using a 364.3-km nondispersion shifted fiber and an erbium-doped fiber amplifier with an output of about +20 dBm to test the system configuration. The CPFSK modulation conditions for the design of repeaterless long-span systems are discussed from the viewpoints of the maximum input power as restricted by SBS laser diode linewidth, and chromatic dispersion in the transmission fiber.<
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