Abstract

Femtosecond fiber lasers (FLs) are also required to have high energies to achieve high quality laser processing of difficult-to-cut materials such as carbon-fiber-reinforced plastics (CFRPs). Our present work develops an all fiber coherent beam combining (CBC) system to achieve a high energy femtosecond FL beyond pulse-energy limits due to nonlinear effects in rare-earth-doped fibers [1]. CBC is a power-addition technology that obtains high energy density and high beam quality because it integrates multiple laser beams in a mono-light wave [2]. However, the CBC of femtosecond pulses is technically difficult because ultrashort-pulse lasers have very low coherence due to their broad spectrums. Therefore, we developed a novel all fiber CBC system that can precisely control fiber lengths, and attempted high-efficient and stable CBC of femtosecond pulses by the system.

© 2015 IEEE