Giant Brillouin gain in frozen CS2 capillaries

TL;DR

This paper introduces a novel frozen CS2 liquid-core fiber platform that achieves exceptionally high Brillouin gain, enabling low-power photonic signal processing and quantum optomechanics applications with meter-scale interaction lengths.

Contribution

The study demonstrates a reversible freezing technique to significantly enhance Brillouin gain in fiber optics, surpassing previous limitations and enabling new low-power photonic technologies.

Findings

Achieved Brillouin gain of 434 W-1m-1 in frozen CS2 fiber

Realized an optoacoustic memory at sub-nanojoule energies

Maintained low optical losses with a fully spliced fiber architecture

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.