Unrepeatered transmission over 415 km at 2.5 Gbit/s with Raman gain and +26.5 dBm launch power

2.5 Gbit/s transmission is demonstrated over a mixed fibre system without using remote optically pumped amplifiers (ROPAs). The use of NRZ data with clock pre-chirp, stimulated Brillouin scattering (SBS) suppression and dispersion compensation enables a +26.5 dBm signal to be launched into fibre. A 980 nm pumped preamplifier with a 3.5 dB noise figure and additional Raman gain at the receiver realises a system length of 392 km with an effective sensitivity of -45.2 dBm. When the system fibre length is increased to 415 km, an error rate is demonstrated which if forward error correction (FEC) were used would give error free transmission