Stimulated Brillouin Scattering

Summary

Stimulated Brillouin Scattering can be considered an outgrowth of Stimulated Raman scattering. As with Raman scattering, Brillouin scattering can be either spontaneous or a parametric interaction of optical photons with an acoustic phonon. Spontaneous scattering is typically measured perpendicular to light beam's propagation direction. Spontaneous emission will be the source of initial Stokes photons that can be increased by stimulated gain, as in a Brillouin amplifier. The primary impact of Stokes entering at the end of the fiber is to set the phase for the pump‐created Stokes wave. As with other amplifiers, when there is feedback, amplifier becomes oscillator. The high gain in Brillouin amplifiers enables their Brillouin laser threshold to be lowest of any nonlinearity, if the laser input has a narrow linewidth. A very different alternative to linear fiber is a ring Brillouin laser, which can be integrated into a single photonic chip.