Han Jinsil, Kim Jihoon, Lee Seul-Lee, Choi Sungwook, Lee Yong Wook
School of Electrical Engineering, Pukyong National University, Busan 48513, Korea.
Interdisciplinary Program of Biomedical Mechanical & Electrical Engineering, Pukyong National University, Busan 48513, Korea.
J Nanosci Nanotechnol. 2021 Mar 1;21(3):1948-1954. doi: 10.1166/jnn.2021.18895.
In this paper, we propose a bend-insensitive optical fiber sensor capable of separately measuring strain and temperature by incorporating a fiber transmission grating (FTG) inscribed on high birefringence photonic crystal fiber (HBPCF) with a CO laser. The FTG was fabricated by exposing unjacketed HBPCF to CO laser pulses using the line-by-line technique. The FTG inscribed on HBPCF, referred to as the HBPC-FTG, has two resonance dips with different wavelengths depending on input polarization. These two resonance dips were utilized as sensor indicator dips denoted by a shorter wavelength dip (SD) and a longer wavelength dip (LD). The strain and temperature responses of the SD and LD were investigated in a strain range of 0 to 3105 μ and a temperature range of 30 to 85 °C, respectively. The measured strain sensitivities of the SD and LD at room temperature (25 °C) were approximately -0.46 and -0.58 pm/μ, respectively. Similarly, the measured temperature sensitivities of the SD and LD without applied strain (0 μ) were ˜5.99 and ˜9.89 pm/°C, respectively. Owing to their linear and independent responses to strain and temperature, strain and temperature changes applied to the HBPC-FTG can be simultaneously estimated from the measured wavelength shifts of the two indicator dips (i.e., SD and LD) using their predetermined strain and temperature sensitivities. Moreover, bend-induced spectral variations of the SD and LD were also examined in a curvature range of 0-4.705 m, and it was observed that both dips showed little wavelength shift due to applied bending. Thus, it is concluded from the experimental results that the fabricated HBPC-FTG can be employed as a cost-effective sensor head for bend-insensitive discrimination of strain and temperature.
在本文中，我们提出了一种对弯曲不敏感的光纤传感器，该传感器通过将刻写在高双折射光子晶体光纤（HBPCF）上的光纤传输光栅（FTG）与CO激光相结合，能够分别测量应变和温度。FTG是通过使用逐行技术将无护套的HBPCF暴露于CO激光脉冲中来制造的。刻写在HBPCF上的FTG，称为HBPC - FTG，根据输入偏振具有两个不同波长的共振凹陷。这两个共振凹陷被用作传感器指示凹陷，分别由较短波长凹陷（SD）和较长波长凹陷（LD）表示。分别在0至3105 μ的应变范围和30至85 °C的温度范围内研究了SD和LD的应变和温度响应。在室温（25 °C）下，SD和LD测得的应变灵敏度分别约为 - 0.46和 - 0.58 pm/μ。同样，在无应变（0 μ）时，SD和LD测得的温度灵敏度分别约为5.99和9.89 pm/°C。由于它们对应变和温度的线性和独立响应，可以使用预先确定的应变和温度灵敏度，根据两个指示凹陷（即SD和LD）测得的波长偏移同时估算施加到HBPC - FTG上的应变和温度变化。此外，还在0 - 4.705 m的曲率范围内检查了SD和LD的弯曲引起的光谱变化，并且观察到由于施加弯曲，两个凹陷的波长偏移都很小。因此，从实验结果可以得出结论，所制造的HBPC - FTG可以用作一种经济高效的传感器头，用于对应变和温度进行弯曲不敏感的区分。
