Paper highlighted in OSA´s “Spotlight on Optics”

Spotlight on Optics highlights research published in their journals—  only two papers from all journals each month! OSA journals are foremost in the field, with consistently high Institute for Scientific Information (ISI) rankings among the top 20.

First author Thorsten Goebel (AG Nolte) summarizes the results of the research work on which the award-winning publication is based, which was carried out together with colleagues from the Fraunhofer IOF:

“Targeted filtering of unwanted narrowband light sources (e.g. excitation lasers for Raman spectroscopy or hydroxyl emission lines in the Earth's upper atmosphere) is a major challenge in multimode fiber optic systems. The use of multicore fibers enables single-mode performance with multimodal input and output by means of a photonic lantern. Thus, fiber Bragg gratings can be used here, which show their excellent filtering properties only in single-mode optical fibers. Typically, however, multicore fibers show large variations in core geometry between the different cores, leading to variations in the resonant wavelength of the fiber Bragg gratings. The commercial 7-core fiber used in this work had exactly these deviations, which were to be corrected by targeted post-processing using ultrashort pulsed laser radiation. Since this was not sufficient, a multicore fiber design with 12 cores was developed in cooperation with Fraunhofer IOF, which should show the lowest possible core-to-core deviations. In the resulting multicore fibers, narrowband filters were successfully inscribed in all cores, which showed an outstanding overlap in the resonance wavelength. This was made possible by arranging the cores along a circle and localized material patterning using ultrashort pulsed laser radiation. The results demonstrate the low core-to-core deviations of the fabricated multicore fibers and thus enable the fabrication of matched wavelength filters.”