A low-cost strain sensor system based on a long-period fiber grating written by high-frequency CO 2 laser pulses

Author(s):  
Yun-Jiang Rao ◽  
Jing-Yi Li
2020 ◽  
Vol 1547 ◽  
pp. 012005
Author(s):  
J F Rojas ◽  
S Valencia ◽  
J A Montoya-Cardona ◽  
J L Galvis ◽  
N D Gomez-Cardona

2020 ◽  
Vol 111 ◽  
pp. 103520
Author(s):  
Yang Yi ◽  
Yiwei Ma ◽  
Senyu Wang ◽  
Xiaoyang Li ◽  
Hongjia Zhu ◽  
...  

2021 ◽  
Vol 21 (3) ◽  
pp. 1883-1889
Author(s):  
Min Seok Kim ◽  
Do Kyung Kim ◽  
Jihoon Kim ◽  
Seul-Lee Lee ◽  
Sungwook Choi ◽  
...  

Here we report an optical fiber sensor capable of performing strain-insensitive simultaneous measurement of bending and temperature using a long-period fiber grating (LPFG) inscribed on doubleclad fiber (DCF) with a CO2 laser at ˜10.6 μm. The LPFG inscribed on DCF, referred to as a DC-LPFG, was fabricated by scanning CO2 laser pulses on an unjacketed DCF with a specific period. Due to co-directional mode coupling, the fabricated DC-LPFG has discrete attenuation bands widely distributed over hundreds of nanometers. Among these wavelength-dependent loss dips, adjacent two dips with different resonance wavelengths were selected as sensor indicators for the measurement of bending and temperature. For these two indicator dips designated as dips A and B, their bending and temperature responses were investigated in a curvature range of 4.90 to 21.91 m−1 and a temperature range of 30 to 110 °C. With increasing bending applied to the DC-LPFG at room temperature, dips A and B showed different blue shifts. The bending sensitivities of dips A and B were measured to be approximately −0.77 and 0.51 nm/m−1, respectively. Unlike the bending response, they showed red shifts of different amounts with increasing ambient temperature, while the sensor head (i.e., the DC-LPFG) remained straight without any applied bending. The temperature sensitivities of dips A and B were measured to be ˜0.094 and ˜0.078 nm/°C, respectively. Owing to their linear and independent responses to bending and temperature, bending and temperature changes applied to the DC-LPFG could be simultaneously estimated from the measured wavelength shifts of the two indicator dips using their pre-determined bending and temperature sensitivities. Moreover, in a strain range of 0 to 2200 με (step: 200 με), strain-induced spectral variations of dips A and B were also measured, and the strain sensitivities of dips A and B were evaluated as approximately −0.028 and −0.013 pm/με, respectively. These strain-induced wavelength shifts were so small that they had little effect on the measurement results of bending and temperature. Thus, it is concluded that the fabricated DC-LPFG can be employed as a cost-effective sensor head for strain-insensitive separate measurement of bending and temperature.


2019 ◽  
Vol 58 (9) ◽  
pp. 2366 ◽  
Author(s):  
Osanori Koyama ◽  
Makoto Matsui ◽  
Takuro Kagawa ◽  
Yuta Suzuki ◽  
Kanami Ikeda ◽  
...  

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