Fiber pressure sensors based on periodical mode coupling effects
Document Type
Conference Proceeding
Publication Date
10-3-2005
Abstract
Fiber optic sensor technology offers the possibility of implementing low weight, high performance and cost effective health and damage assessment for infrastructure elements. Common fiber sensors are based on the effect of external action on the spectral response of a Fabry-Perot or a Bragg grating section, or on the modal dynamics in multimode (MM) fiber. In the latter case, the fiber itself acts as the sensor, giving it the potential for large range coverage. We were interested in this type of sensor because of its cost advantage in monitoring structural health. In the course of the research, a new type of a rugged modal filter device, based on off-center splicing, was developed. This device, in combination with a MM fiber, was found to be a potential single point-pressure sensing device. Additionally, by translating the pressing point along a MM sensing fiber with a constant load and speed, a sinusoidal intensity modulation was observed. This harmonic behavior, during load translation, is explained by the theory of mode coupling and dispersion. The oscillation period, Λ∼0.43 mm, obtained at 980 nm in a Corning SMF-28™ fiber, corresponds to the wavevector difference, Δβ, between the two-coupled modes, Λ = 2π/Δβ. An additional outcome of the present research is the observation that the response of the loaded MM fiber is strongly dependent on the polarization state of the light traveling along the MM fiber due to different response of the modes to polarization active elements. Our main conclusions are that in MM fiber optic sensor design, special cautions need to be taken in order to stabilize the system, and that the sensitivity along a MM fiber sensor is periodic with a period of ∼ 0.4 - 0.5 mm, depending on various fiber parameters and excited modes.
Identifier
25144499088 (Scopus)
Publication Title
Proceedings of SPIE the International Society for Optical Engineering
External Full Text Location
https://doi.org/10.1117/12.598818
ISSN
0277786X
First Page
239
Last Page
247
Volume
5758
Recommended Citation
Lotem, Haim; Wang, Wen C.; Wang, Michael; Schaafsma, David; Skolnick, Bob; and Grebel, Haim, "Fiber pressure sensors based on periodical mode coupling effects" (2005). Faculty Publications. 19537.
https://digitalcommons.njit.edu/fac_pubs/19537
