Stokes linewidth narrowing by stimulated Brillouin scattering in liquid media

As an effective means to obtain a narrow-linewidth laser, stimulated Brillouin scattering (SBS) has not only the advantages of pulse compression but also controllable Stokes linewidth output. However, most research thus far has been focused on continuous-wave lasers, with little emphasis on short-pulse lasers. This work demonstrates that the Brillouin gain linewidth and pump power density are the primary factors affecting the linewidth of the Stokes pulse. As the pump power density increases, the Stokes linewidth tends to narrow and approaches the pump linewidth. This is the first study to reveal that the pump linewidth is the limiting factor in narrowing the Stokes linewidth. The Stokes linewidths of different liquid media were compared, and it was found that media with a wide Brillouin gain linewidth can be used to obtain lasers with a wider range of linewidths.