Laser Lineshape Dependence on the Evolution of Brillouin Gain Spectrum in Single Mode Silica Optical Fibers
Abstract
We describe an experimental investigation of the Brillouin spectra from several different single mode optical fibers (SMF) at IR communication wavelengths ((λ)=1550nm). Using two different lasers and a heterodyne detection setup, we have followed the evolution of the Brillouin lineshapes as a function of the signal power injected, from the spontaneous into the stimulated regime. The Stimulated Brillouin scattering (SBS) thresholds fall in the range from 3.2mW to 39.4mW and are found to depend primarily on the electrostrictive coefficient, length, core area and laser linewidth. In the spontaneous regime, several acoustic resonance modes are observed in addition to the main Brillouin peak, which are found to shift away from the main peak as the fiber core is made smaller. With increasing incident power, the process becomes stimulated and the additional modes disappear, leaving only the main Brillouin peak with a linewidth approximately 10 times narrower than that in the spontaneous regime. In the stimulated regime, the lineshape of the Brillouin spectra is also found to be identical to the input laser lineshape, with a resolution bandwidth that is equal to the SBS linewidth of the medium (7-12 MHz). This work was supported by NSF--DMR 9974031.
- Publication:
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APS March Meeting Abstracts
- Pub Date:
- March 2000
- Bibcode:
- 2000APS..MAR.G9007Y