In this paper we investigate the effects of viscoelasticity on both the strength and resonance wavelength of two fibre Bragg gratings (FBGs) inscribed in microstructured polymer optical fibre (mPOF) made of undoped PMMA. Both FBGs were inscribed under a strain of 1% in order to increase the material photosensitivity. After the inscription the strain was released and the FBGs spectra were monitored. We initially observed a decrease of the reflection down to zero after which it began to increase. After that, strain tests were carried out to confirm the results and finally the gratings were monitored for a further 120 days, with a stable reflection response being observed beyond 50 days.
Bibliographical note© 2015 Optical Society of America.
This paper was published in Optics Letters and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://www.opticsinfobase.org/ol/abstract.cfm?URI=ol-40-7-1476. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law.
Funding: Marie Curie Intra European Fellowship included in the 7th Framework Program of the European Union (project PIEF-GA-2011-302919) and by the People Program (Marie Curie Actions) of the European Union’s Seventh Framework Program FP7/2007-2013/under REA grant agreement no. 608382.
Sáez Rodríguez, D., Nielsen, K., Bang, O., & Webb, D. J. (2015). Time-dependent variation of fiber Bragg grating reflectivity in PMMA-based polymer optical fibers. Optics Express, 40(7), 1476-1479. https://doi.org/10.1364/OL.40.001476