A high-sensitivity curvature sensing configuration is implemented by using a fiber Mach-Zehnder interferometer (MZI) with D-shaped fiber Bragg grating (FBG). A segment of D-shaped fiber is fusion spliced into a single mode fiber at both sides, and then a short FBG is inscribed in the D-shaped fiber. The fiber device yields a significant spectrum sensitivity as high as 87.7 nm/m -1 to the ultralow curvature range from 0 to 0.3 m -1 , and can distinguish the orientation of curvature experienced by the fiber as the attenuation dip producing either a blue or red wavelength shift, by virtue of the asymmetry of D-shaped fiber cladding. In addition, by tracking both resonant wavelengths of the MZI and embedded FBG, the temperature and curvature can be measured simultaneously.
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Funding: This work was supported in part by the National Natural Science Foundation of China under Grants 61505165 and 61775182, in part by the Natural Science Basic Research Plan in Shaanxi Province of China under Grant 2016JQ6032, and in part by Marie Skłodowska-Curie Individual Fellowships in the European Union’s Horizon 2020 Research and Innovation Programme under Grant 660648.
- curvature measurement
- D-shaped fiber
- fiber Bragg grating (FBG)
- Fiber gratings
- Mach-Zehnder interferometer (MZI)
- Optical fiber sensors
- Optical fibers
- Temperature measurement
- Temperature sensors