Sound waves propagating in one direction break light transmission reciprocity

https://www.laserfocusworld.com/fiber-optics/article/14286781/sound-waves-propagating-in-one-direction-break-light-transmission-reciprocity

"boosts signal quality and purity of optical vortices—signals transmitted in optical communications... mode-division-multiplexed communications, optical tweezers, vortex lasers, or quantum manipulation systems... device by design nonreciprocal—it’s based on light-sound interactions within spiral optical fiber to naturally break reciprocity of light waves propagating forth and back... nonlinear interaction, Brillouin scattering... light-sound interactions for OAM modes... nonreciprocal isolator or one-way amplifier"

Related: Physicists Generated Sound Waves That Travel in One Direction Only

https://www.sciencealert.com/physicists-generated-sound-waves-that-travel-in-one-direction-onl