2.2 ELECTRICAL, ELECTRONIC, INFORMATION ENGINEERING
In this Letter, we demonstrate a high-sensitivity vector bend sensor based on a fiber directional coupler. The fiber directional coupler is composed of two parallel waveguides inscribed within a no-core fiber (NCF) by a femtosecond laser. Since the two written waveguides have closely matched refractive indices and geometries, the transmission spectrum of the fiber directional coupler possesses periodic resonant dips. Such a fiber directional coupler exhibits a good bending-dependent spectral shift response due to its asymmetric structure. Experimental results show that bending sensitivities of -97.11 nm/m-1 and 58.22 nm/m-1 are achieved for the 0° and 180° orientations in the curvature range of 0-0.62 m-1, respectively. In addition, the proposed fiber directional coupler is shown to be insensitive to external humidity changes, thus improving its suitability in high-accuracy bending measurements.
Tian, Ke; Zhang, Mingyuan; Zhao, Chuanzhein; Li, Huibin; Li, Shilong; Jiang, Yuxuan; Farrell, Gerald; and Wang, Pengfei, "High-Sensitivity Vector Bend Sensor Based on a Fiber Directional Coupler Inscribed by a Femtosecond Laser" (2023). Articles. 43.
National Natural Science Foundation of China (NSFC) (62225502, 61935006, 62090062, 62205085); Heilongjiang Provincial Natural Science Foundation of China (LH2020F028); Fundamental Research Funds for the Central Universities (3072022TS2504); 111 Project (B13015); Heilongjiang Touyan Innovation Team Program; Science Foundation Ireland under the Centres research program for the MaREI project (SFI/12/RC/2302_P2)
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