Berlin 2001 – scientific programme
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Q: Quantenoptik
Q 32: Poster: Laser Spectroscopy
Q 32.1: Poster
Friday, April 6, 2001, 12:30–15:00, AT2
Decay length measurements of evanescent fields in the case of molecular resonances — •Dirk Scheel1, Ulrike Willer1, Ashwini Kumar Sharma2, and Wolfgang Schade1 — 1Institut für Physik und Physikalische Technologien, TU Clausthal, Leibnizstrasse 4, 38678 Clausthal-Zellerfeld, www.pe.tu-clausthal.de/AGSchade/index.html — 2Department of Physics and Centre for Laser Technology, Indian Institute of Technology Kanpur, Kanpur 208016 (UP), India
With a near-field-optical microscope the decay length of an evanescent field for an O2-absorption line at ambient air is measured.
The wavelength of a Littrow laser is tuned across 764 nm to reach different spectral positions of the oxygen absorption line. Due to a change in the index of refraction and the absorption coefficient there is a variation of a factor of around 1.7 in the decay length of the evanescent field when the absorption line is scanned from on-resonance to off-resonance positions. Measurements and theoretical calculations are compared.