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Femtosecond laser pulse written long period gratings in large mode area fibers

: Heck, M.; Krämer, R.G.; Richter, D.; Goebel, T.A.; Matzdorf, C.; Tünnermann, A.; Nolte, S.


Institute of Electrical and Electronics Engineers -IEEE-:
Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference, CLEO/Europe-EQEC 2017 : 25-29 June 2017, Munich, Germany
Piscataway, NJ: IEEE, 2017
ISBN: 978-1-5090-6736-7
ISBN: 978-1-5090-6737-4
Conference on Lasers and Electro-Optics Europe (CLEO) <2017, Munich>
European Quantum Electronics Conference (EQEC) <2017, Munich>
Fraunhofer IOF ()

This paper reports on investigations regarding the inscription of long period gratings (LPG) into large mode area (LMA) fibers. The refractive index change is directly induced into the core region of the fiber (Nufern GDF 20 μm core, 400 μm cladding), using the point by point inscription technique at a laser wavelength of 800 nm and a pulse duration of 150 fs. By adapting the translation speed of the fiber with respect to the objective and repetition rate of the laser system, it is possible to create a continuous modification whereby the periodicity Λ can be adjusted by an external shutter. In a first experiment an LPG with Λ=865 μm is realized. The result shows distinct resonant peaks e.g. at 1080 and 1120 nm with an attenuation of roughly -6 dB. The index modification is well located in the core region.