Suppression of stimulated brillouin backscattering by psk modulation for high-power optical transmission

High-power optical fibre transmission combined with coherent detection offers a significant advantage in terms of length between repeaters. However, nonlinear optical effects limit the level of power into a fibre to a few milliwatts. The paper reports on the initiation and suppression of stimulated Brillouin scattering using phase shift keying at 1320 nm, discusses the effect of signal statistics on the level at which the nonlinear effect appears, and introduces and experimentally confirms an upper bound on the digital sum variation of codes. It emerges that the code requirements for high power, high bit rate, coherent systems can easily be met.