Jena 2013 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
K: Fachverband Kurzzeitphysik
K 5: Laserstrahlwechselwirkung und Laseranwendungen
K 5.1: Vortrag
Dienstag, 26. Februar 2013, 14:00–14:15, HS 4
Selective mode filter in a large mode area fiber inscribed by ultrashort laser pulses — •Ria G. Krämer1, Christian Voigtländer1, Jens U. Thomas1, Daniel Richter1, Andreas Tünnermann1,2, and Stefan Nolte1,2 — 1Insitute of Applied Physics, Abbe Center of Photonics, Friedrich-Schiller-University Jena, Max-Wien-Platz 1, D-07743 Jena, Germany — 2Fraunhofer Institute for Applied Optics and Precision Engineering, Albert-Einstein-Str. 7, D-07745 Jena, Germany
We demonstrate a selective mode filter in a few mode large mode area (LMA) fiber inscribed directly with ultrashort pulses. The mode filter consists of refractive index modifications written alongside the core, into the cladding, where the change of the refractive index is of the same order of magnitude as the difference between core and cladding. The presence of the modulation causes a perturbation of the guiding modes, leading to coupling between the modes. Depending on length and position of the modification, light will couple from the higher order to the fundamental mode or vice versa. To characterize the functionality of the mode filter, a femtosecond inscribed fiber Bragg grating (FBG) providing spectral separation of the core modes was used. First, the FBG was written, followed then by the mode filter. During the inscription process the reflection spectrum of the FBG was measured in situ using a supercontinuum source, providing a length dependent feedback of the mode filter. The reflectivity of the individual modes yields information about the suppression of the modes. We could filter separately either the fundamental or higher order mode.