Suppressing Stimulated Brillouin Scattering in Multimode Fibers via Wavefront shaping

Abstract

We demonstrate theoretically that SBS threshold can be increased significantly by many-mode excitations in multimode fibers. We experimentally focus multimode excitation to a diffraction limited spot, leading to high SBS threshold with good beam quality.

Suppressing Stimulated Brillouin Scattering by Selective Mode Excitation in Multimode Fibers

“…2.3). With output beam control, our method allows utilizing highly multimode fibers with even larger cores (diameter > 100 µm), leading to orders of magnitude increase in threshold [42]. In terms of output focusing, near-unity (> 95%) power concentration in the focal spot has been achieved with complete control of input fields to an MMF [43].…”

“…To understand the mechanism of SBS suppression with multimode excitation, we have developed a multimode SBS theory (detailed derivation in [42]). Consider Brillouin scattering of a forward-propagating photon (signal) in fiber mode l to a backward photon (Stokes) in mode m via emission of a forward acoustic phonon at frequency Ω.…”

“…(Ω) is determined by the spatial overlap of optical modes m and l with acoustic modes in the fiber [42]. We order the modes by their propagation constants from high to low.…”

“…(Ω) and the signal power P l [42]. The SBS threshold is defined by the transmitted signal power at which a significant fraction of the input power is lost to backward Stokes.…”

Mitigating stimulated Brillouin scattering in multimode fibers with focused output via wavefront shaping

“…To understand the mechanism of SBS suppression with multimode excitation, we have developed a multimode SBS theory (detailed derivation in ref. 48). Consider Brillouin scattering of a forwardpropagating photon (signal) in fiber mode l to a backward photon (Stokes) in mode m via emission of a forward acoustic phonon at frequency Ω.…”