Stimulated Brillouin Review: Invented 50 Years Ago and Applied Today

Figure 12

(i) Main fiber cavity: Optical circulator 1, Brillouin gain SM fiber, another circulator combining with Rayleigh feedback fiber (5-km) with continuously changing core diameter and dispersion for enhanced Rayleigh DFB. (ii) Fiber subloop: EDFA amplifies each backward Stokes wave [adapted from [14]].