Brillouin fibre laser enhanced by Raman amplification

A multiple-wavelength Brillouin fibre laser is demonstrated, with channel spacings of ∼10.5 GHz, using Raman amplification in dispersion-shifted optical fibre. More than 20 frequency lines with ∼2 kHz linewidths are obtained using a 14.5 km length of fibre and a 1.3 MHz linewidth Brillouin pump. Gain depletion due to amplified spontaneous emission limits the total number of cascaded Brillouin lines. At high Raman pump powers, the laser produces a pulse train at the repetition rate corresponding to the cavity round-trip time.