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ToF-SIMS imaging of dopant diffusion in optical fibers
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2003 (English)In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 203, 648-651 p.Article in journal (Refereed) Published
Abstract [en]

Applications of optical fibers in telecommunication and sensing are rapidly emerging where the fiber properties are related to the controlled addition of dopants such as germanium, phosphorous, fluorine and erbium. The modern ToF-SIMS instrument, with its high sensitivity and high lateral resolution, has shown to be an excellent tool to directly analyze cross-sections of as-manufactured fibers. The present work describes ToF-SIMS imaging of the dopant distribution in fluorine, germanium and rare-earth doped fibers where dopants are confined to a few mum in the core. The increased fluorine diffusion in the fluorine doped fibers due to chemical reactions with hydroxyl groups was examined. This process is utilized in the manufacture of thermally stable chemical composition fiber Bragg gratings. We were able to produce ToF-SIMS elemental images with a lateral resolution around 0.5 mum showing the detailed distribution of the dopants.

Place, publisher, year, edition, pages
2003. Vol. 203, 648-651 p.
Keyword [en]
ToF-SIMS, imaging, optical fibers, fiber bragg gratings, diffusion, dopant
National Category
Physical Sciences
URN: urn:nbn:se:kth:diva-13205ISI: 000180527300145OAI: diva2:321835
QC 20100602Available from: 2010-06-02 Created: 2010-06-02 Last updated: 2010-06-07Bibliographically approved
In thesis
1. Photosensitivity, chemical composition gratings and optical fiber based components
Open this publication in new window or tab >>Photosensitivity, chemical composition gratings and optical fiber based components
2002 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

The different topics of this thesis include high-temperaturestable fiber Bragg gratings, photosensitivity and fiber basedcomponents.

Fiber Bragg gratings (FBG) are wavelength dispersiverefractive index structures manufactured through UV exposure ofoptical fibers. Their applications range from WDM filters,dispersion compensators and fiber laser resonators fortelecommunication applications to different types of point ordistributed sensors for a variety of applications.

One aim of this thesis has been to study a new type of FBGreferred to as chemical composition grating. These gratingsdiffer from other types of FBG in that their refractive indexstructure is attributed to a change in the chemicalcomposition. Chemical composition gratings have shown to beextremely temperature stable surviving temperatures in excessof 1000 oC. Photosensitivity of pure silica and germanium-dopedcore fibers in the presence of hydroxyl groups has also beenstudied and different types of fiber based components have beendeveloped.

The main result of the thesis is a better understanding ofthe underlying mechanism of the formation of chemicalcomposition gratings and their decay behavior at elevatedtemperatures. The refractive index modulation is caused by aperiodic change in the fluorine concentration, which has beenverified through time-of-flight secondary-ion-mass spectrometryand through studies of the decay behavior of chemicalcomposition gratings. A model based on diffusion of dopants hasbeen developed, which successfully predicts the thermal decayat elevated temperatures. Studies of the dynamics of chemicalcomposition grating formation have resulted in a manufacturingtechnique that allows for reproducible gratingfabrication.

The main results regarding photosensitivity is a method tosignificantly increase the effect of UV radiation on standardtelecommunications fiber. The method, referred to asOH-flooding, has also been applied to pure-silica core fibersresulting in the first report of strong grating formation insuch fibers.

Finally, research into different schemes for developingfiber-based components has resulted in two types of singlefiber integrated Mach-Zehnder interferometers; one passiveinterferometer that can be used as an optical filter and oneactive interferometer controlled with internal metalelectrodes.

Keywords:optical fibers, fiber Bragg gratings,photosensitivity, thermal stability, fiber sensors, chemicalcomposition gratings, fiber components, Mach-Zehnderinterferometer, optical switch, optical modulator.

Place, publisher, year, edition, pages
Stockholm: KTH, 2002. xii, 77 p.
Trita-FYS, ISSN 0280-316X ; 2239
optical fibers, fiber bragg gratings, photosensitivity, thermal stability
National Category
Natural Sciences
urn:nbn:se:kth:diva-3436 (URN)91-7283-397-1 (ISBN)
Public defence
2002-12-06, 00:00
QC 20100607Available from: 2002-12-03 Created: 2002-12-03 Last updated: 2010-06-07Bibliographically approved

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Fokine, MichaelMargulis, Walter
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