High power, single frequency DFB fibre laser with low relative intensity noise

We have demonstrated a high power, single frequency DFB fibre laser in MOPA configuration. More than 5 W of output power was obtained without any noticeable degradation of optical signal-to-noise ratio (OSNR), linewidth or relative intensity noise (RIN). OSNR as high as 60 dB was achieved after the MOPA while the laser RIN remains constant (within experimental error limit) to -147 dB/Hz. We have also shown that SBS threshold increases exponentially as the fibre length decreases. Thus output power of the order of tens of watts is feasible from such a source by limiting the amplifier length to a few meters.