Dependence of stimulated Brillouin scattering on the bandwidth, mode number, and mode separation of a laser

Based on the multi-axial theory of stimulated Brillouin scattering (SBS), a group of coupled wave equations without limitation to the mode separation of a laser is deduced when the random initial phases of the axial modes are introduced for SBS pumped by a free operation laser. The coupling coefficient between two axial modes is obtained, and the dependences of the threshold and reflectivity of broadband SBS on the bandwidth, the mode number, the mode separation of the laser, are simulated numerically. The SBS threshold and reflectivity are dependent not only on the laser bandwidth, but also on the mode number and the mode separation of the laser.