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Ultra-sensitive surface absorption spectroscopy using sub-wavelength diameter optical fibers

2007; Optica Publishing Group; Volume: 15; Issue: 19 Linguagem: Inglês

10.1364/oe.15.011952

1094-4087

F. Warken, E. Vetsch, Dieter Meschede, M. Sokołowski, Arno Rauschenbeutel,

Spectroscopy and Laser Applications

The guided modes of sub-wavelength diameter air-clad optical fibers exhibit a pronounced evanescent field. The absorption of particles on the fiber surface is therefore readily detected via the fiber transmission. We show that the resulting absorption for a given surface coverage can be orders of magnitude higher than for conventional surface spectroscopy. As a demonstration, we present measurements on sub-monolayers of 3,4,9,10-perylene-tetracarboxylic dianhydride (PTCDA) molecules at ambient conditions, revealing the agglomeration dynamics on a second to minutes timescale.