機械誘起長周期光ファイバグレーティングの反射型カスケード構造の各種センシング特性を解明した香港科技大学との研究成果が IEEE Sensors Journal に掲載されました。
A. K. Das, H. Lee, K. Noda, Y. Mizuno, C. K. Y. Leung, and K. Nakamura, “Potential of mechanically induced cascaded long-period grating structure for reflectometric pressure, strain, and temperature sensing,” IEEE Sens. J., vol. 20, no. 18, pp. 10539-10546 (2020).
We present the first report on reflectometric optical fiber sensing based on mechanically induced cascaded long-period grating (LPG) structure. This method utilizes in-house designed mechanical casings and a bare fiber. When a fiber is sandwiched between the casings and pressed by tightening screws, an LPG is induced due to a photo-elastic effect. By exploiting Fresnel refection at a fiber end, a cascaded LPG structure can be implemented using a single LPG, enabling reflectometric configuration. When this sensor is subjected to external physical processes, the attenuation bands change clearly, and their shift can be used for non-destructive evaluations. We show experimentally that this sensor can measure loads of up to 10 N without producing any permanent change in the fiber properties, indicating its pressure sensing capability. We also show that this sensor can potentially measure strain and temperature. In our experiments, the strain and temperature sensitivities are 9.4 nm/% and 0.045 nm/°C, respectively.