Jin Xiren, Xiang Zihang, Lu Chupeng, Zhang Shuo, Rui Zeju, Yi Yang, Xu Xian, Wang Jiabin, Sun Cuiting, Geng Tao, Guan Chunying, Yang Xinghua, Sun Weimin, Yuan Libo
Opt Express. 2021 Jul 19;29(15):22813-22822. doi: 10.1364/OE.427251.
In this letter, a highly sensitive bending sensor based on an embedded multimode D-shaped long period fiber grating (EMD-LPFG) is proposed. The novel sensor is applied to carry out vector bending measurement. The proposed LPFG is fabricated by polishing on the prepared structure which is formed by periodically splicing between single mode fiber (SMF) and multimode fiber (MMF). Since the cross section of the embedded MMF is D-shaped, we named it EMD-LPFG. Due to the asymmetric modulation of the refractive index on the fiber by the CO laser, the sensor has the ability to distinguish the bending directions, and the MMFs provide higher bending response. The experimental transmission spectrum can match the simulation results well. The experimental results show that the average bending sensitivities in three orthogonal directions are 70.21 nm/m (0°), 9.75 nm/m (90°), -12.04 nm/m (180°) and 9.98 nm/m (270°), respectively. Meanwhile, the temperature sensitivity is 30 pm/°C in the range of 25 °C to 75 °C. According to the ultra-compact structure with the total length of 2.5 mm, high bending sensitivity and ability to distinguish the bending direction, the novel sensor has potential in bending measurement.
在这封信中，提出了一种基于嵌入式多模D形长周期光纤光栅（EMD-LPFG）的高灵敏度弯曲传感器。该新型传感器用于进行矢量弯曲测量。所提出的长周期光纤光栅是通过在由单模光纤（SMF）和多模光纤（MMF）周期性熔接形成的预制结构上进行抛光制成的。由于嵌入式多模光纤的横截面为D形，我们将其命名为EMD-LPFG。由于CO激光对光纤折射率的非对称调制，该传感器具有区分弯曲方向的能力，并且多模光纤提供更高的弯曲响应。实验传输光谱与模拟结果能很好地匹配。实验结果表明，在三个正交方向上的平均弯曲灵敏度分别为70.21 nm/m（0°）、9.75 nm/m（90°）、-12.04 nm/m（180°）和9.98 nm/m（270°）。同时，在25°C至75°C范围内温度灵敏度为30 pm/°C。基于总长2.5 mm的超紧凑结构、高弯曲灵敏度和区分弯曲方向的能力，该新型传感器在弯曲测量方面具有潜力。
