Adaptable Optical Fiber Displacement-Curvature Sensor Based on a Modal Michelson Interferometer with a Tapered Single Mode Fiber

A compact, highly sensitive optical fiber displacement and curvature radius sensor is presented. The device consists of an adiabatic bi-conical fused fiber taper spliced to a single-mode fiber (SMF) segment with a flat face end. The bi-conical taper structure acts as a modal coupling device between...

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Bibliographic Details
Published in:Sensors (Basel, Switzerland) Switzerland), 2017-06, Vol.17 (6), p.1259
Main Authors: Salceda-Delgado, G, Martinez-Rios, A, Selvas-Aguilar, R, Álvarez-Tamayo, R I, Castillo-Guzman, A, Ibarra-Escamilla, B, Durán-Ramírez, V M, Enriquez-Gomez, L F
Format: Article
Language:English
Subjects:
Adiabatic flow
Axial stress
Cladding
Curvature
Displacement
Optical fibers
Periodic variations
Refractivity
Sensors
Spectral sensitivity
Visibility
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Summary:A compact, highly sensitive optical fiber displacement and curvature radius sensor is presented. The device consists of an adiabatic bi-conical fused fiber taper spliced to a single-mode fiber (SMF) segment with a flat face end. The bi-conical taper structure acts as a modal coupling device between core and cladding modes for the SMF segment. When the bi-conical taper is bent by an axial displacement, the symmetrical bi-conical shape of the tapered structure is stressed, causing a change in the refractive index profile which becomes asymmetric. As a result, the taper adiabaticity is lost, and interference between modes appears. As the bending increases, a small change in the fringe visibility and a wavelength shift on the periodical reflection spectrum of the in-fiber interferometer is produced. The displacement sensitivity and the spectral periodicity of the device can be adjusted by the proper selection of the SMF length. Sensitivities from around 1.93 to 3.4 nm/mm were obtained for SMF length between 7.5 and 12.5 cm. Both sensor interrogations, wavelength shift and visibility contrast, can be used to measure displacement and curvature radius magnitudes.
ISSN:1424-8220
1424-8220
DOI:10.3390/s17061259