Implications of high power losses in IR femtosecond laser inscribed fibre Bragg gratings

K.T. O'Mahoney, A.S. Main, D.J. Webb, A. Martínez, D.A. Flavin

Research output: Chapter in Book/Published conference outputConference publication


We report on high power issues related to the reliability of fibre Bragg gratings inscribed with an infrared femtosecond laser using the point-by-point writing method. Conventionally, fibre Bragg gratings have usually been written in fibres using ultraviolet light, either holographically or using a phase mask. Since the coating is highly absorbing in the UV, this process normally requires that the protective polymer coating is stripped prior to inscription, with the fibre then being recoated. This results in a time consuming fabrication process that, unless great care is taken, can lead to fibre strength degradation, due to the presence of surface damage. The recent development of FBG inscription using NIR femtosecond lasers has eliminated the requirement for the stripping of the coating. At the same time the ability to write gratings point-by-point offers the potential for great flexibility in the grating design. There is, however, a requirement for reliability testing of these gratings, particularly for use in telecommunications systems where high powers are increasingly being used in long-haul transmission systems making use of Raman amplification. We report on a study of such gratings which has revealed the presence of broad spectrum power losses. When high powers are used, even at wavelengths far removed from the Bragg condition, these losses produce an increase in the fibre temperature due to absorption in the coating. We have monitored this temperature rise using the wavelength shift in the grating itself. At power levels of a few watts, various temperature increases were experienced ranging from a few degrees up to the point where the buffer completely melts off the fibre at the grating site. Further investigations are currently under way to study the optical loss mechanisms in order to optimise the inscription mechanism and minimise such losses.

Original languageEnglish
Title of host publicationProceedings of SPIE - The International Society for Optical Engineering
EditorsHans G. Limberger, M. John Mattewson
Number of pages7
ISBN (Print)0819462497, 9780819462497
Publication statusPublished - 23 May 2006
EventReliability of Optical Fiber Components, Devices, Systems, and Networks III - Strasbourg, United Kingdom
Duration: 3 Apr 20064 Apr 2006

Publication series

NameSPIE proceedings
ISSN (Print)0277-786X


ConferenceReliability of Optical Fiber Components, Devices, Systems, and Networks III
Country/TerritoryUnited Kingdom

Bibliographical note

K. T. O'Mahoney ; A. S. Main ; D. J. Webb ; A. Martinez and D. A. Flavin
"Implications of high power losses in IR femtosecond laser inscribed fiber Bragg gratings", Proc. SPIE 6193, Reliability of Optical Fiber Components, Devices, Systems, and Networks III, 61930Z (May 24, 2006).

Copyright 2006 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.



Dive into the research topics of 'Implications of high power losses in IR femtosecond laser inscribed fibre Bragg gratings'. Together they form a unique fingerprint.

Cite this