An alignment-free fiber-coupled microsphere resonator for gas sensing applications

M. Gregor1, C. Pyrlik2 , R. Henze1, A. Wicht2, A. Peters2,3, and O. Benson1

Published in:

Appl. Phys. Lett., vol. 96, no. 231102 (2010).

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Abstract:

In this paper we report on the assembly of a robust sensor system consisting of a polystyrene microsphere resonator attached to an optical fiber taper. Since the sphere is only supported by the micrometer-sized fiber no further alignment is necessary. This results in a thermally and mechanically well isolated optical resonator system with quality factors as high as 6×105. The narrow resonances of whispering gallery modes supported by the polystyrene resonators shift with temperature at a rate of 3.8 GHz/K. Thus, a sensitive thermometer is established which allows to detect the surrounding gas via its characteristic thermal conductivity.

1 Nano-Optik, Institut für Physik, Humboldt-Universität zu Berlin, 10117 Berlin, Germany
2 Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Straße 4, 12489 Berlin, Germany
3 Optical Metrology, Institut für Physik, Humboldt-Universität zu Berlin, 10117 Berlin, Germany

Keywords:

gas sensors, optical resonators, whispering gallery modes.