Abstract
A curvature fiber optic sensor using a two-core fiber (TCF) is proposed and demonstrated. The TCF is designed to operate as a directional coupler with one core located exactly at the center of the fiber and the other off-axis, but close to the center of the fiber. This design allows straightforward splicing of the TCF to single mode fibers (SMF), and alignment of the off-axis core is not strictly required for optimum operation. The sensor is fabricated by simply splicing a 5 cm long section of TCF between two SMF sections, which provides a sinusoidal spectral response. When the fiber is bent, the coupling parameters are modified due to stress-optic and effective length effects, effectively blue-shifting the sinusoidal spectral response of the sensor and allowing for the measurement of curvature. The sensor exhibits linear response and a sensitivity of -137.87 nm/m(-1) for curvature ranging from 0 to 0.27 m(-1), making it suitable to measure small curvatures with high sensitivity.
Highlights
The measurement of relative displacements and deformations play an important role in different areas such as aerospace, geophysics, nanotechnology, and structural health monitoring
Among grating-based curvature sensors, those using fiber Bragg gratings (FBG) as the sensing element can operate in large ranges of curvature but exhibit low sensitivity
A novel, simple, and cost-effective curvature sensor based on a two-core fiber (TCF) has been demonstrated
Summary
The measurement of relative displacements and deformations play an important role in different areas such as aerospace, geophysics, nanotechnology, and structural health monitoring. A growing interest on curvature sensors based on optical fibers has arisen due to their well known superior advantages, such as immunity to external electromagnetic interference, compactness, high sensitivity, and in situ measurements. In the case of specialty fibers, a curvature sensor based on a double-cladd fiber has been reported to operate in the range from 0 to 1.48 m−1 with a sensitivity of 10.15 nm/m−1 [5]. An in-fiber Mach-Zehnder interferometer for curvature sensing has been reported to operate in the range from 0.1 to 1.7 m−1 with a sensitivity of −2.56 nm/m−1 [8] This sensor is simple to fabricate, a relatively long fiber is needed to induce significant changes in the interferometric pattern. The sensor exhibits linear response in the range from 0 to 0.2653 m−1, with a sensitivity of −137.8763 nm/m−1, which is at least nine times better as compared to the most sensitive sensors reported to date [3, 4]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
