Bending characteristics of fiber long-period gratings with cladding index modified by femtosecond laser

Thomas D.P. Allsop*, Mykhaylo Dubov, Amós Martínez, Filip Floreani, Igor Khrushchev, David J. Webb, Ian Bennion

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


A femtosecond laser has been used to asymmetrically modify the cladding of fiber containing long-period gratings. Following modification, devices in single-mode fiber are shown to be capable of sensing the magnitude and direction of bending in one plane by producing blue and red wavelength shifts depending upon the orientation of the bend. The resulting curvature sensitivities were -1.62 and +3.82 nm·m. Devices have also been produced using an elliptical core fiber to study the effects of the cladding modification on the two polarization eigenstates. A cladding modification applied on the fast axis of the fiber is shown to affect the light in the fast axis much more significantly than the light in the orthogonal state; this behavior may ultimately lead to a sensor capable of detecting the direction of bending in two dimensions for applications in shape sensing. © 2006 IEEE.

Original languageEnglish
Pages (from-to)3147-3154
Number of pages8
JournalJournal of Lightwave Technology
Issue number8
Publication statusPublished - 1 Aug 2006

Bibliographical note

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  • curvature measurement
  • long-period fiber gratings
  • polarization dependence


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