Pre-compensation of thermally induced refractive index changes in a depressed core fully aperiodic large-pitch fiber for high average power operation

in: Optics Letters (2021)
Malleville, Marie-Alicia; Leconte, Baptiste; Dauliat, Romain; Jamier, Raphael; Schwuchow, Anka; Wondraczek, Katrin; Roy, Philippe
To prevent the thermally induced spatial beam degradation occurring in high-power fiber lasers and amplifiers, index-depressed core “fully aperiodic large-pitch fibers” (FA-LPFs) have been designed and fabricated. In contrast to previous experimental works performed on FA-LPFs, in which the active core and the surrounding cladding material are quasi-index-matched, the core refractive index is in slight depression compared to the surrounding material (Δn ≈-3x10-5). Thus, the index-depressed fiber core tends first to behave as an anti-guide, preventing light from being properly guided into it. However, by increasing the absorbed pump power, the thermal load induces a parabolic refractive index change sufficient to compensate for the -3x10-5 index depression in the core, enabling a robust single-mode amplification at high average power. As a proof of concept, using a 110 µm depressed core FA-LPF, M2 values of 1.3 were demonstrated in amplifier configuration from 60Wto a maximal value of 170Wof emitted average power only limited by the available pump power.

Third party cookies & scripts

This site uses cookies. For optimal performance, smooth social media and promotional use, it is recommended that you agree to third party cookies and scripts. This may involve sharing information about your use of the third-party social media, advertising and analytics website.
For more information, see privacy policy and imprint.
Which cookies & scripts and the associated processing of your personal data do you agree with?

You can change your preferences anytime by visiting privacy policy.