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Guiding light in fluids


In optical biosensors the interaction between light and target molecules is typically very weak. In order to improve this interaction we are using a novel anti-resonant waveguide concept, in which the core region has a lower refractive index than the cladding layers in contrast to conventional waveguides with high refractive index core. With this concept the light can be guided within the target-containing medium, thereby enabling an extended interaction length. An anti-resonant waveguide is especially compatible with a fluidic biosensor because the fluidic channel itself can be used as the core of the anti-resonant waveguide. We explain the concept of anti-resonant optical guided modes in the ray picture of light and calculate the confinement factors inside the fluid. Experiments have shown that these modes can be excited by collimating excitation light under an appropriate angle onto the waveguide structure. Scanning the intensity profile at the end facet of the waveguide confirms the anti-resonant guided optical wave (ARGOW) model.

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Schmidt, O. ; Bassler, M. ; Kiesel, P. ; Johnson, N. M. ; Doehler, G. Guiding light in fluids. Applied Physics Letters. 2006 April; 88: 151109.


Copyright © American Institute of Physics, 2006. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Applied Physics Letters and may be found at http://dx.doi.org/10.1063/1.2195075.