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K: Fachverband Kurzzeitphysik
K 8: Laseranwendungen und Lasermaterialbearbeitung II
K 8.4: Talk
Thursday, February 28, 2013, 14:45–15:00, HS 4
Inscription of tailored fiber Bragg gratings with a deformed wave-front — •Christian Voigtländer1, Ria Krämer1, Jens Thomas1, Daniel Richter1, and Stefan Nolte1,2 — 1Institute of Applied Physics, Abbe Center of Photonics, Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, 07743 Jena, Germany — 2Fraunhofer Institute for Applied Optics and Precision Engineering, Alber-Einstein-Straße 7, 07745 Jena, Germany
Within the last years the interest in fiber Bragg gratings (FBGs) has ceaselessly grown, as they are excellent components for all-integrated fiber lasers. The fabrication with ultrashort laser pulses makes possible to directly induce them in active doped fibers. Thus, splicing within the laser cavity is not necessary anymore.
A common inscription technique for FBGs is the phase mask method, where an interference pattern is generated by overlapping the first diffraction orders behind the mask. This pattern is focused by a cylindrical lens into the core of the fiber. However, the grating period is predetermined by the phase mask, and another period usually requires another phase mask.
This drawback can be overcome by deforming the wave-front of the inscription beam before the phase mask. The aberrations lead to a tuned period of the interference pattern. A defocused beam can shift the period, while a coma induces a chirp of the grating period. Thus, the phase mask technique becomes more flexible.