High power fiber amplifiers employing Large Mode Area fibers are currently limited to a few kW, in part, due to Transverse Mode Instability. There’s a need to scale fiber amplifiers beyond a few kW, which would require Transverse Mode Instabilities to be mitigated.
This LLNL invention proposes a new microstructured large mode area fiber design that enhances the confinement of the core mode while strongly suppressing thermal or scattering mediated dynamic couplings with higher order modes thought to be responsible for generating undesirable Transverse Mode Instabilities. The design accomplishes higher order mode suppression and core mode confinement by using a hybrid approach with low index barriers and high index rings around the core. The high index rings provide enhanced confinement through an Anti-Resonant Reflection Optical Waveguide (ARROW) mechanism.
Image Caption: Schematic of six-ring design for IL-13352
- Enables high power fiber amplifiers to be scaled beyond a few kW.
- Mitigates instabilities through a novel fiber structural design.
High power fiber lasers and amplifiers for materials processing.
LLNL has patent(s) on this invention.
U.S. Patent No. 11,462,878 All Solid Hybrid ARROW Fiber published 10/4/2022