Strongly coupled stimulated Brillouin amplification with flying focus

Damage to compression gratings poses a fundamental limit to chirped pulse amplification in high-power laser systems. Plasma-based compressors using strongly coupled stimulated Brillouin scattering (scSBS) offer a damage-free alternative, but their effectiveness has been hindered by instabilities that constrain interaction length. In this study, we report the first experimental demonstration of scSBS amplification driven by a flying focus in a 3 mm plasma channel. The flying focus is generated using chromatic aberration from spherical lenses, with its velocity precisely measured by an interferometric ionization method achieving 6.6 fs timing resolution. At a focus velocity near −c, scSBS amplification is realized at pump and seed intensities more than two orders of magnitude lower than in conventional schemes, yielding a conversion efficiency of 14.5%. The result is also supported by two-dimensional particle-in-cell simulations. These results demonstrate the effectiveness of flying focus as a tool for extending interaction lengths and enabling efficient plasma-based laser amplification at reduced intensities.