ABSTRACT
Stimulated Brillouin scattering (SBS) has been a subject of interest because of its ability to achieve distributed Brillouin optical fiber sensors (Diaz et al. 2008, Soto et al. 2010, Dong et al. 2009, Dong et al. 2011), Brillouin slow light (Okawachi et al. 2005, Lu et al. 2007, Dong et al. 2008, Song et al. 2005, Zhu et al. 2005) and amplification of weak signals (Gao et al. 2011, Gao et al. 2012). SBS is classically described as a nonlinear process involving a pump wave, a Stokes wave and an acoustic wave, where the angular frequencies ωp of the pump wave, ωs of the Stokes wave, and Ω of the acoustic wave satisfy Ω = ωp - ωs (Agrawal 2001, Boyd 2010). Because of damping of the acoustic wave, the bandwidth of SBS amplification is spectrally broadened around the Brillouin resonant frequency, resulting in a Brillouin gain bandwidth of a few tens of MHz in a silica single-mode optical fiber. This resonant characteristic has been exploited for narrowband filter and amplifier (Tanemura 2002, Lee 2007), and spectrum evolution of amplified spontaneous Brillouin scattering has also been investigated in previous studies (Gaeta 1991, Yeniay 2002), which show that the Stokes wave of the spontaneous Brillouin scattering is characterized by spectrum narrowing as pump power is increased.
