Spin-orbit interaction in nanofiber-based Brillouin scattering

Angular momentum is an important physical property that plays a key role in light-matter interactions such as spin-orbit interaction. Here, we investigate theoretically and experimentally the interaction between circularly polarized optical (spin) transverse vortex acoustic wave (orbital) using Brillouin backscattering silica nanofiber. We specifically explore state of polarization induced by TR21 torso-radial mode carries orbital angular momentum. Using full-vectorial theoretical model, predict observe two operating regimes for which backscattered signal either depolarized or depending on input pump polarization. demonstrate when thus spin momentum, undergoes handedness reversal circular due to optoacoustic conservation overall