Heck, M.M.HeckGauthier, J.-C.J.-C.GauthierVallee, R.R.ValleeTünnermann, A.A.TünnermannBernier, M.M.BernierNolte, S.S.Nolte2022-03-142022-03-142018https://publica.fraunhofer.de/handle/publica/40407110.1364/BGPPM.2018.BW3A.52-s2.0-85051265351A concept to mitigate parasitic self lasing effects in mid-IR fiber amplifiers by means of efficient long period fiber gratings is shown. Using tightly confined ultrashort laser pulses at 800 nm the gratings are directly inscribed into the core of a fluoride glass fiber. Strong attenuation peaks down to -22 dB, with sharp and predictable spectral resonances, were obtained. The gratings reveal great potential to improve the laser performance concerning average output power and attainable spectral range.en620conference paper