Pico-strain-level dynamic perturbation measurement using πFBG sensor

Deepa Srivastava; Bhargab Das

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arXiv · 1710.04206

Pico-strain-level dynamic perturbation measurement using πFBG sensor

Deepa Srivastava·Bhargab Das

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Abstract

Interferometric interrogation technique realized for conventional fiber Bragg grating (FBG) sensors is historically known to offer the highest sensitivity measurements, however, it has not been yet explored for π-phase-shifted FBG (πFBG) sensors. This, we believe, is due to the complex nature of the reflection/transmission spectrum of a πFBG, which cannot be directly used for interferometric interrogation purpose. Therefore, we propose here an innovative as well as simple concept towards this direction, wherein, the transmission spectrum of a πFBG sensor is optically filtered using a specially designed fiber grating. The resulting filtered spectrum retains the entire characteristics of a πFBG sensor and hence the filtered spectrum can be interrogated with interferometric principles. Furthermore, due to the extremely narrow transmission notch of a πFBG sensor, a fiber interferometer can be realized with significantly longer path difference. This leads to substantially enhanced detection limit as compared to sensors based on a regular FBG of similar length. Theoretical analysis demonstrate that high resolution weak dynamic strain measurement down to 4 pε/sqrt(Hz) is easily achievable.

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Deepa Srivastava, Bhargab Das. 2017-10-11. Pico-strain-level dynamic perturbation measurement using πFBG sensor. https://arxiv.org/abs/1710.04206

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