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AKB: Biologische Physik
AKB 20: Nano-Biomaterials and Devices
AKB 20.8: Vortrag
Donnerstag, 30. März 2006, 12:00–12:15, ZEU 255
Raman Sensors using Photonic Crystal Fibers for Chemical and Biological Applications — •John Erland Østergaard1, Stig Christensen2, Kasper Jørgensen2, Søren Hassing2, Thomas Søndergaard3, Stefan Banke Ovesen1, and Karsten Rottwitt4 — 1University of Southern Denmark, Fysisk Institut, Campusvej 55, DK-5230 Odense M — 2Engineering College of Odense, Niels Bohrs Alle 1, DK-5230 Odense M — 3Aalborg University, Institute of Physics and Nanotechnology, DK-9220 Aalborg Øst — 4Technical University of Denmark, COM, DK-2800 Kgs. Lyngby
The recent development in photonic-crystal-fibers (PCF) is currently explored for new types of optical sensors taking advantage of introducing a liquid in the PCF for enhanced sensitivity for Raman signals generated from the liquid. For a Raman sensor, a large air-core PCF with air-holes running along the fiber is considered. It is possible to guide light strongly localized to the large central air-hole via the Bragg effect[1,2]. In our calculations for holes filled with water (n=1.33 compared to silica n=1.45), it is also possible to guide light confined to the core region of the fiber due to the band gap properties of the cladding material. Three frequency ranges for Raman sensing are identified where light is guided well in the core region. In the case where the liquid has a larger refractive index than glass, the PCF supports a mode localized to the liquid-filled core region of the fiber above a cut-off frequency, as for standard fibers. Experimental examples of Raman generation in the PCF for different light propagation regimes is discussed. [1] R.F. Cregan et al, Science, 285, 1537 (1999). [2] Broeng et al., Opt. Lett. 25, 96 (2000).