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Increased sensitivity in fiber-based spectroscopy using carbon-coated fiber
KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
KTH, School of Engineering Sciences (SCI), Applied Physics.
2012 (English)In: Optics Express, ISSN 1094-4087, Vol. 20, no 27, 28049-28055 p.Article in journal (Refereed) Published
Abstract [en]

Carbon-coated optical fibers are used here for reducing the luminescence background created by the primary-coating and thus increase the sensitivity of fiber-based spectroscopy systems. The 2-3 orders of magnitude signal-to-noise ratio improvement with standard telecom fibers is sufficient to allow for their use as Raman probes in the identification of organic solvents.

Place, publisher, year, edition, pages
2012. Vol. 20, no 27, 28049-28055 p.
Keyword [en]
Raman Probe Designs, Optical-Fibers, Silica Fibers, Luminescence
National Category
Engineering and Technology
URN: urn:nbn:se:kth:diva-116811DOI: 10.1364/OE.20.028049ISI: 000314911400010ScopusID: 2-s2.0-84872032750OAI: diva2:601430
Swedish Research Council

QC 20130129

Available from: 2013-01-29 Created: 2013-01-28 Last updated: 2014-05-16Bibliographically approved
In thesis
1. Increased Functionality of Optical Fibers for Life-Science Applications
Open this publication in new window or tab >>Increased Functionality of Optical Fibers for Life-Science Applications
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The objective of this thesis work is to increase the functionality of optical fibers for possible applications in life-sciences. Optical fibers are a promising technology for use in biology and medicine. They are low-costwaveguides, flexible and have a small cross-section. They can guide high-power light with low loss in a micrometer core-size. These features make fibers attractive for minimally-invasive,in-vivostudies. The backwards guidance of the optical signal allows for real-time monitoring of the distance to the scattering targets and to study the environment through Raman scattering and fluorescence excitation. The longitudinal holes introduced in the fibers can be used,for instance,for delivery of medicine to a specific regionof a body. They could even be used for the extractionof species considered interesting for further analysis, for example, studyingcells that may be cancer-related.

This thesis deals with four main topics. First, a demonstration is presented of the combination of high-power light guidance for ablation, low-power light reflectometry for positioning, and for liquid retrieval in a single fiber. It was found that in order to exploit the microfluidic possibilities available in optical fibers with holes, one needs to be able to combine fluids and light in a fiber without hindering the low-loss light guidance and the fluid flow. Secondly, one should also be able to couple light into the liquids and backout again. This is the subject of another paper in the present thesis. It was also observed that laser excitation through a fiber for the collection of a low-intensity fluorescence signal was often affected by the luminescence noise createdby the primary-coating of the fiber. This problem makes it difficult to measure low light-levels, for example, from single-cells. Athirdpaper in this thesis then describes a novel approach to reduce the luminescence from the polymer coating of the fiber, with the use of a nanometer-thick carbon layer on the cladding surface. Finally, exploiting some of the results described earlier, an optical fiber with longitudinal holes is used for the excitation, identification and for the collection of particles considered being of interest. The excitation light is guided in the fiber, the identification is performed by choosing the fluorescent particles with the appropriate wavelength, and, when a particle of interest is sufficiently near the fiber-tip, the suction system is activated for collection of the particle with good specificity.

It is believed that the work described in this thesis could open the doors for applications in life-sciences and the future use of optical fibers for in-vivo studies.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2014. xii, 63 p.
TRITA-FYS, ISSN 0280-316X ; 2014:15
Fiberoptics, microstructured fiber, fiber - based optofluidics, laser ablation, microfluidics, reflectometry, fluorescence detection, fiber - based spectroscopy
National Category
Other Physics Topics
Research subject
urn:nbn:se:kth:diva-145319 (URN)978-91-7595-122-5 (ISBN)
Public defence
2014-05-21, sal FB5, AlbaNova Universitetscentrum, Roslagstullsbacken 21, Stockholm, 10:00 (English)

QC 20140516

Available from: 2014-05-16 Created: 2014-05-15 Last updated: 2014-05-16Bibliographically approved

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