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Proceedings Paper

Fiber Bragg grating inscription with DUV femtosecond exposure and two beam interference
Author(s): Martin Becker; Joachim Bergmann; Sven Brückner; Eric Lindner; Manfred Rothhardt; Kay Schuster; Jens Kobelke; Sonja Unger; Hartmut Bartelt; Luis A. Fernandes; Paulo V. S. Marques
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Paper Abstract

Fiber Bragg gratings (FBGs) are today fundamental components in fiber optics. They can be used as sensors, in signal processing, e.g. telecom applications, as wavelength stabilizers in fiber lasers or in dispersion compensators. However, there are applications where the demand for fiber Bragg gratings is not compatible with standard photosensitivity techniques like germanium doping or hydrogen loading. Examples are their use as laser-mirrors in spliceless all fiber fiber-laser solutions or the fiber Bragg grating inscription in suspended core all silica fibers for evanescent field sensing. Fiber Bragg grating inscription with femtosecond-laser exposure is a challenging new method to realize grating structures for waveguides made of materials which do not provide UV-photosensitivity. Especially fs-IR-inscription has been demonstrated for Bragg grating inscription in a variety of material systems such as boron-silica glass, sapphire and pure silica glass. The feasibility of the phase mask FBG inscription technique with DUV femtosecond lasers was also shown, which allows grating inscription even in pure silica microstructured fibers. The phase mask inscription method requires that the fiber will be placed directly behind the phase mask. While the laser beam should be focused onto the fiber to support nonlinear material interaction, this inscription method also leads to phase mask degradations, presumably due to non-bridging oxygen holes (NBOH). Our solution to avoid the mask degradation is to increase the space between fiber and phase mask by using a Talbot-interferometer. Another advantage is the wavelength versatility of this inscription setup. Due to the short temporal coherence length of the femtosecond pulses, the angular alignment variability of the interferometer mirrors is limited and restrictions concerning the wavelength versatility of the interferometer arise. Grating arrays in pure silica suspended core fibers are demonstrated as an example for the versatility of the inscription arrangement.

Paper Details

Date Published: 4 August 2009
PDF: 10 pages
Proc. SPIE 7386, Photonics North 2009, 73862Y (4 August 2009); doi: 10.1117/12.838605
Show Author Affiliations
Martin Becker, IPHT Jena (Germany)
Joachim Bergmann, IPHT Jena (Germany)
Sven Brückner, IPHT Jena (Germany)
Eric Lindner, IPHT Jena (Germany)
Manfred Rothhardt, IPHT Jena (Germany)
Kay Schuster, IPHT Jena (Germany)
Jens Kobelke, IPHT Jena (Germany)
Sonja Unger, IPHT Jena (Germany)
Hartmut Bartelt, IPHT Jena (Germany)
Luis A. Fernandes, INESC Porto (Portugal)
Paulo V. S. Marques, INESC Porto (Portugal)

Published in SPIE Proceedings Vol. 7386:
Photonics North 2009
Réal Vallée, Editor(s)

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