In this preprint we experimentally demonstrate the freezing of CS2-filled and fully sealed liquid core optical fibers to achieve a giant Brillouin gain. We utilize this high gain to create an optoacoustic memory with very low power usage and illustrate how this new platform can help boost the efficiency of most Brillouin based application. The paper can be found here.

Authors: Simon Seiderer*, Andreas Geilen*, Luan Sliwa*, Linqiao Gan, Xue Qi, Mario Chemnitz, Markus A. Schmidt, and Birgit Stiller (* these authors contributed equally)

Abstract: 
Stimulated Brillouin-Mandelstam scattering offers exceptional capabilities for photonic signal processing, but current platforms demand performance trade-offs between long interaction lengths, high gain, low optical losses, and practical implementation. Here, we demonstrate a novel platform based on the reversible freezing of a carbon disulfide filled liquid-core optical fiber. This approach delivers a giant in-fiber Brillouin gain of 434 W-1m-1 with a linewidth of 24 MHz, while maintaining low propagation losses in a fully spliced architecture and providing the potential for meter-scale interaction lengths. Leveraging this gain, as a proof of principle, we realize an optoacoustic memory operating at sub-nanojoule pulse energies - more than two orders of magnitude lower than state-of-the-art implementations. This power reduction is universal for Brillouin-based fiber applications in general and will enable low-power photonic signal processing and neuromorphic computing, efficient microwave photonics and sensing, as well as in-fiber quantum optomechanics-based technologies.