Factors influencing the temperature sensitivity of PMMA based optical fiber Bragg gratings


The Bragg wavelength of a PMMA based fiber grating is determined by the effective core index and the grating pitch, which, in temperature sensing, depend on the thermo-optic and thermal expansion coefficients of PMMA. These two coefficients are a function of surrounding temperature and humidity. Amorphous polymers including PMMA exhibit a certain degree of anisotropic thermal expansion. The anisotropic nature of expansion mainly depends on the polymer processing history. The expansion coefficient is believed to be lower in the direction of the molecular orientation than in the direction perpendicular to the draw direction. Such anisotropic behavior of polymers can be expected in drawn PMMA based optical fiber, and will lead to a reduced thermal expansion coefficient and larger temperature sensitivity than would be the case were the fiber to be isotropic. Extensive work has been carried out to identify these factors. The temperature responses of gratings have been measured at different relative humidity. Gratings fabricated on annealed and non-annealed PMMA optical fibers are used to compare the sensitivity performance as annealing is considered to be able to mitigate the anisotropic effect in PMMA optical fiber. Furthermore an experiment has been designed to eliminate the thermal expansion contribution to the grating wavelength change, leading to increased temperature sensitivity and improved response linearity.

Publication DOI: https://doi.org/10.1117/12.2054210
Divisions: College of Engineering & Physical Sciences > Aston Institute of Photonics Technology (AIPT)
Additional Information: Wei Zhang and David J. Webb, "Factors influencing the temperature sensitivity of PMMA based optical fiber Bragg gratings", Micro-structured and Specialty Optical Fibres III, Kyriacos Kalli; Alexis Mendez, Editors, Proc. SPIE 9128 (2014). Copyright 2014 Society of Photo-Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic electronic or print 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. DOI: http://dx.doi.org/10.1117/12.2054210
Event Title: Micro-structured and specialty optical fibres III
Event Type: Other
Event Dates: 2014-04-14 - 2014-04-15
Uncontrolled Keywords: anisotropic expansion,fiber Bragg grating,PMMA based optical fiber,thermo-optic effect,Applied Mathematics,Computer Science Applications,Electrical and Electronic Engineering,Electronic, Optical and Magnetic Materials,Condensed Matter Physics
ISBN: 978-1-62841076-1
Last Modified: 05 Jul 2024 07:14
Date Deposited: 19 Jan 2015 16:43
Full Text Link: http://proceedi ... ticleid=1868440
Related URLs: http://www.scop ... tnerID=8YFLogxK (Scopus URL)
PURE Output Type: Conference contribution
Published Date: 2014-05-19
Authors: Zhang, Wei (ORCID Profile 0000-0002-3584-8541)
Webb, David J. (ORCID Profile 0000-0002-5495-1296)



Version: Published Version

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