Characterisation of femtosecond laser inscribed long period gratings in photonic crystal fibre

Thomas D.P. Allsop, Kyriacos Kalli, Kaiming Zhou, Graham Smith, Lai Yicheng, Mykhaylo Dubov, Kate Sugden, David J. Webb, Ian Bennion, Michael Komodromos

Research output: Chapter in Book/Published conference outputConference publication


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 preprocessing 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.
Original languageEnglish
Title of host publicationPhotonic crystal fibers II
EditorsKyriacos Kalli, Waclaw Urbanczyk
ISBN (Print)978-0-8194-7188-8
Publication statusPublished - 21 Apr 2008
EventPhotonic Crystal Fibers III - Prague, Czech Republic
Duration: 22 Apr 200923 Apr 2009

Publication series

NameSPIE proceedings
ISSN (Print)0277-786X


ConferencePhotonic Crystal Fibers III
Country/TerritoryCzech Republic

Bibliographical note

Allsop, Thomas D.P.; Kalli, Kyriacos; Zhou, Kaiming; Smith, Graham; Yicheng, Lai; Dubov, Mykhaylo; Sugden, Kate; Webb, David J.; Bennion, Ian; Komodromos, Michael. "Characterisation of femtosecond laser inscribed long period gratings in photonic crystal fibre". Photonic crystal fibers II. ed. Kyriacos Kalli; Waclaw Urbanczyk. Vol. 6990 SPIE, 2008. (SPIE proceedings).

Copyright 2008 Society of Photo-Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited.


  • absorption
  • architectural design
  • bending
  • crystal atomic structure
  • crystal whiskers
  • detectors
  • fiber Bragg gratings
  • fiber optic sensors
  • laser pulses
  • lasers
  • light refraction
  • lithography
  • multiphoton
  • processes
  • nanostructured materials
  • optical properties
  • photonic crystals
  • photonics
  • powders
  • power generation
  • pulsed laser applications
  • pulsed laser deposition
  • refractive index
  • refractometers
  • sensors
  • ultrashort pulses
  • (Mo Y) doping
  • bend sensors
  • characterisation
  • embedded fiber Bragg grating
  • external perturbations
  • femtosecond lasers
  • femtosecond inscription
  • fibre Bragg grating sensors
  • grating periods
  • grating structures
  • high energy pulses
  • high intensity
  • long period grating
  • multiphoton absorption
  • photonic crystal fibers
  • photonic crystal fibre
  • potential applications
  • refractive index changes
  • sensing devices
  • single modes
  • spectral features
  • temperature cross-sensitivity
  • void generation


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