Stimulated Brillouin Scattering, observed in an optical transmission system using fibre lasers as signal sources, was suppressed by external phase modulation. The threshold power of SBS in a single mode fibre with 8.3-micrometers diameter was as low as 2 dBm due to a narrow spectral linewidth of a fibre laser. At 20 MHz phase-modulation, modulation voltages above 5.3V suppressed the first order Stokes more than 25 dB. RF spectrums of the fibre laser phase-modulated at or above 5.3V showed multiple sets of sideband components higher than the carrier frequency component in amplitude. The minimum spectral bandwidth of a fibre laser with 20 kHz bandwidth was broadened to 120 MHz at this modulation condition. The results signified broadening of the effective spectral linewidth of the fibre laser by phase modulation.

Date Published: 19 October 2001
PDF: 5 pages
Proc. SPIE 4579, Optical Fiber and Planar Waveguide Technology, (19 October 2001); doi: 10.1117/12.444916

Published in SPIE Proceedings Vol. 4579:
Optical Fiber and Planar Waveguide Technology
Shuisheng Jian; Yanming Liu, Editor(s)