https://doi.org/10.1140/epjst/e2014-02241-8
Regular Article
Crystalline MgF2 whispering gallery mode resonators for enhanced bulk index sensitivity
1 Institute for Optics, Information and Photonics, University of Erlangen-Nuremberg, Germany, Günther-Scharowsky-Str. 1, 91058 Erlangen, Germany
2 Max-Planck-Institute for the Science of Light, Günther-Scharowsky-Str. 1/Bldg. 24, 91058 Erlangen, Germany
3 School in Advanced Optical Technologie, Paul-Gordan-Str. 6, 91052 Erlangen, Germany
a e-mail: Richard.Zeltner@mpl.mpg.de
Received: 11 July 2014
Revised: 4 August 2014
Published online: 6 October 2014
We report on experiments on refractrometric sensing with crystalline Whispering Gallery Mode (WGM) resonators made of magnesium fluoride, which has a refractive index that is only slightly larger than that of water (Δn ≈ 0.05). The resulting evanescent field of a WGM resonator placed in an aqueous environment penetrates therefore deep into the surrounding medium, which makes it a promising candidate for sensing applications. We measured a bulk index sensitivity of 1.09 nm/RIU (refractive index unit) in a resonator with a radius of R = 2.91 mm and intrinsic Q-factors of more than 108 in aqueous environments. Furthermore, we describe the fabrication process of crystalline WGM resonators.
© EDP Sciences, Springer-Verlag, 2014
