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Dynamics of long-period gratings tuned with internal fiber electrodes
KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.ORCID iD: 0000-0003-3933-4406
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2011 (English)In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 36, no 5, 633-635 p.Article in journal (Refereed) Published
Abstract [en]

The physics of electrically switched long-period grating in a twin-hole fiber with internal electrodes is studied. Dynamic measurements for the two polarizations show how the grating spectra shift in time due to the mechanical stress and heat transfer in the core and the cladding.

Place, publisher, year, edition, pages
2011. Vol. 36, no 5, 633-635 p.
National Category
Atom and Molecular Physics and Optics
Identifiers
URN: urn:nbn:se:kth:diva-31605DOI: 10.1364/OL.36.000633ISI: 000287912500013Scopus ID: 2-s2.0-79952336688OAI: oai:DiVA.org:kth-31605DiVA: diva2:406290
Funder
Swedish Research CouncilKnut and Alice Wallenberg Foundation
Note
QC 20110325Available from: 2011-03-25 Created: 2011-03-21 Last updated: 2012-11-29Bibliographically approved
In thesis
1. All-fiber modulators for laser applications
Open this publication in new window or tab >>All-fiber modulators for laser applications
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The objective of this thesis was to explore the usefulness of all-fiber modulators for laser applications. The modulators were all based on refractive index change achieved in the core of the studied fiber- components, exploiting either the elasto-optic effect or the electro-optic effect. This was realized with the aid of electrodes inside the fiber cladding close to the core that provided either thermal stress in the core, or an electric field across the core. The electrodes consisted of low melting-point alloys, such as BiSn and AuSn, which were pushed into the hole-fiber, in the liquid state, which then solidified to form solid electrodes filling the entire hole.

Together with an analyzer such as a polarizer or an interferometer the achieved refractive index modulation in the core could then be translated into an amplitude modulation of the guided light, which was subsequently utilized for switching fiber-lasers to generate cavity dumped, Q-switched, or mode-locked pulses. The fast rise/fall-time of a few nanoseconds for the elasto-optic devices was due to the fast thermal expansion of the electrodes. The maximum repetition rate, however, was limited to a few tens of kHz, due to the slow thermal processes for dissipation of the applied energy. The electro-optic fiber components, which displayed similar rise/fall-times on the other hand, showed a much higher cut-off frequency of 16 MHz.

The electro-optic, all-fiber switch was also employed to select single pulses at 1 MHz repetition rate out of a 7 MHz train of pulses. Additionally, simulations using the finite element method were performed in order to gain insight and to explain the underlying processes of the observed response of a long-period grating written in a 2-hole fiber with electrodes, when applying HV-pulses to one of these.

The thesis shows that the studied fiber-components show great potential of becoming complementary devices with high damage threshold for all-fiber laser applications in the future. 

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2012. vii, 77 p.
Series
Trita-FYS, ISSN 0280-316X ; 2012:86
Keyword
All-fiber, fiber optics, modulation, q-switching, mode-locking
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-105863 (URN)978-91-7501-574-3 (ISBN)
Public defence
2012-12-18, FD5, Albanova, Roslagstullsbacken 21, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20121129

Available from: 2012-11-29 Created: 2012-11-28 Last updated: 2015-03-30Bibliographically approved

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Malmström, Mikael

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