Enhancing the humidity response time of polymer optical fiber Bragg grating by using laser micromachining

Xianfeng Chen, Wei Zhang, Chen Liu, Yanhua Hong, David J. Webb

Research output: Contribution to journalArticle

Abstract

The humidity sensors constructed from polymer optical fiber Bragg gratings (POFBG) respond to the water content change in the fiber induced by varying environmental condition. The water content change is a diffusion process. Therefore the response time of the POFBG sensor strongly depends on the geometry and size of the fiber. In this work we investigate the use of laser micromachining of D-shaped and slotted structures to improve the response time of polymer fiber grating based humidity sensors. A significant improvement in the response time has been achieved in laser micromachined D-shaped POFBG humidity sensors. The slotted geometry allows water rapid access to the core region but this does not of itself improve response time due to the slow expansion of the bulk of the cladding. We show that by straining the slotted sensor, the expansion component can be removed resulting in the response time being determined only by the more rapid, water induced change in core refractive index. In this way the response time is reduced by a factor of 2.5.
Original languageEnglish
Pages (from-to)25942-25949
Number of pages8
JournalOptics Express
Volume23
Issue number20
Early online date24 Sep 2015
DOIs
Publication statusPublished - 5 Oct 2015

Bibliographical note

Funding: EU FP7 (314032 and PIRSES-GA-2013-612267); and the project of Sêr Cymru NRN097.

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