Regensburg 2016 – scientific programme

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DF: Fachverband Dielektrische Festkörper

DF 11: Poster

DF 11.6: Poster

Wednesday, March 9, 2016, 18:00–20:00, Poster E

Whispering gallery mode resonators with varying diameter and thickness for enhanced sensitivity — •Sanaz Rastjoo, Sarah Krämmer, Tobias Siegle, Carolin Klusmann, and Heinz Kalt — Institute of Applied Physics, Karlsruhe Institute of Technology (KIT), 76128 Karlsruhe, Germany

In this work we present our latest results on active polymeric whispering gallery mode resonators. The resonators are dye (pyrromethene 597)-doped PMMA (poly (methyl methacrylate)) disks, exhibiting lasing emission when optically pumped. One of the crucial parameters for sensing is the so-called "bulk refractive index sensitivity" (BRIS). Theory predicts that the sensitivity of the resonators increases with decreasing radius, however the quality factor and thus the lasing threshold are affected when the resonators are operated in an aqueous environment. We fabricated resonators with different radii from 25 µm down to 7.5 µm and performed measurements on the lasing threshold and the BRIS. The theoretical expectations could be confirmed by experiments: Resonators with smaller radii showed higher sensitivities but also higher lasing thresholds. Taking both aspects into account resonators with 10 µm radius show sensitivities up to 46.9 nm/RIU while still showing comparably low thresholds. Another approach to enhance the sensitivity of disk resonators is by variation of the disk thickness. We investigated this aspect in our work to further optimize the geometry of the disk resonators for sensing applications.