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Proceedings Paper

Characterisation of femtosecond laser inscribed long period gratings in photonic crystal fibre
Author(s): Tom Allsop; Kyriacos Kalli; Kaiming Zhou; Graham Smith; Yicheng Lai; Michael Dubov; Kate Sugden; David Webb; Ian Bennion; Michael Komodromos
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Paper Abstract

The use of high intensity femtosecond laser sources for inscribing fibre gratings has attained significant interest. The principal advantage of high-energy pulses is their ability for grating inscription in any material type without pre-processing or special core doping - the inscription process is controlled multi-photon absorption, void generation and subsequent local refractive index changes. The formation of grating structures in photonics crystal fibre has proven difficult, as the presence of holes within the fibre that allow wave-guidance impair and scatter the femtosecond inscription beam. Here we report on the consistent manufacture of long period gratings in endlessly single mode microstructure fibre and on their characterisation to external perturbations. Long period gratings are currently the subject of considerable research interest due to their potential applications as filters and as sensing devices, responsive to strain, temperature, bending and refractive index. Compared to the more mature fibre Bragg grating sensors, LPGs have more complex spectra, usually with broader spectral features. On the other hand they are intrinsically sensitive to bending and refractive index. Perhaps more importantly, the fibre design and choice of grating period can have a considerable influence over the sensitivity to the various parameters, for example allowing the creation of a bend sensor with minimal temperature cross-sensitivity. This control is not possible with FBG sensors. Here we compare the effects of symmetric and asymmetric femtosecond laser inscription.

Paper Details

Date Published: 21 April 2008
PDF: 13 pages
Proc. SPIE 6990, Photonic Crystal Fibers II, 69900I (21 April 2008); doi: 10.1117/12.781104
Show Author Affiliations
Tom Allsop, Aston Univ. (United Kingdom)
Kyriacos Kalli, Cyprus Univ. of Technology (Cyprus)
Kaiming Zhou, Aston Univ. (United Kingdom)
Graham Smith, Aston Univ. (United Kingdom)
Yicheng Lai, Aston Univ. (United Kingdom)
Michael Dubov, Aston Univ. (United Kingdom)
Kate Sugden, Aston Univ. (United Kingdom)
David Webb, Aston Univ. (United Kingdom)
Ian Bennion, Aston Univ. (United Kingdom)
Michael Komodromos, Frederick Research Ctr. (Cyprus)

Published in SPIE Proceedings Vol. 6990:
Photonic Crystal Fibers II
Kyriacos Kalli; Waclaw Urbanczyk, Editor(s)

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