Dresden 2011 – scientific programme

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MO: Fachverband Molekülphysik

MO 29: Poster: Electronic Spectroscopy

MO 29.1: Poster

Thursday, March 17, 2011, 16:00–18:00, P1

Temperature Measurements of an Ultra-thin Optical Fiber — •Sebastian Müller, Markus Müller, and Frank Stienkemeier — Physikalisches Institut, Universität Freiburg, Hermann-Herder-Str.3 79104 Freiburg

The use of ultra-thin optical fibers provides a new method for sensitive spectroscopy of molecules attached to surfaces. In the present case PTCDA (3,4,9,10 perylen-tetracarboxylic dianhydride) molecules are deposited on the waist of an optical fiber with a diameter of about 400 nm. As shown in recent publications, the evanescent field of the guided light at the ultra-thin part allows absorption as well as fluorescence spectroscopy with high sensitivity [1,2].

The temperature of the fiber is a relevant factor for the growth and stacking of the molecules on the surface. Hence it is important to measure and control the temperature of the fiber. Because standard temperature sensors are not an option, other methods have to be developed. We use the thermal expansion properties of the fiber as a sensor. The fiber is integrated in a Mach-Zehnder interferometer. By changing the temperature, the optical path length shifts. Analysis of the fringe pattern allows to determine the temperature down to a few degrees Kelvin.

[1] F. Warken et al., Optics Express 15, 11952 (2007)

[2] A. Stiebeiner et al., Optics Express 17, 21704 (2009)