Three-hole microstructured optical fiber for efficient Fiber Bragg Grating refractometer

Description

We present a photosensitive three-hole microstructured optical fiber specifically designed to improve the refractive index sensitivity of a standard Fiber Bragg Grating (FBG) sensor photowritten in the suspended Ge-doped silica core. We describe the specific photowriting procedure used to realize gratings in such a fiber. We then determine their spectral sensitivity to the refractive index changes of material filling the holes surrounding the core. The sensitivity is compared to that of standard FBGs photowritten in a six-hole fiber with a larger core diameter. We demonstrate an improvement of the sensitivity by two orders of magnitude and reach a resolution of 3 x 10-5 and 6 x 10-6 around mean refractive index values of 1.33 and 1.40, respectively.

Abstract

International audience

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