Xiang Shen, Xiongwei Hu, Luyun Yang, Nengli Dai, Jianjun Wu, Fangfang Zhang, Jingang Peng, Haiqing Li, Jinyan Li
Opt Express. 2017 May 1;25(9):10405-10412. doi: 10.1364/OE.25.010405.
We have demonstrated a helical long-period grating (HLPG) manufactured from multicore fiber (MCF) combined with twist and CO-laser heating technology. The MCF we used behaves as a kind of single mode fiber. The nineteen cores of MCF are distributed hexagonally which make the helical structure only exist in core area after heating and twisting. There are several strong couplings between the core and cladding modes at different wavelengths when the grating pitch was 900 µm. The extinction ratio of the main coupling reached 20 dB at 1550 nm. We have investigated the sensor characteristics of the HLPG. It is found that the grating presents clear sensitivity to refractive-index while exhibiting smaller cross-sensitivity to environmental temperature than conventional long-period gratings. The HLPG also shows great potential as a twist sensor, which has a sensitivity up to 0.198 nm/(rad/m) and can apply for measuring twist directions.
我们展示了一种由多芯光纤（MCF）结合扭转和CO激光加热技术制造的螺旋长周期光栅（HLPG）。我们使用的MCF表现为一种单模光纤。MCF的19个芯呈六边形分布，这使得螺旋结构在加热和扭转后仅存在于芯区。当光栅间距为900 µm时，在不同波长下芯模与包层模之间存在几种强耦合。在1550 nm处，主耦合的消光比达到20 dB。我们研究了HLPG的传感器特性。发现该光栅对折射率具有明显的灵敏度，同时与传统长周期光栅相比，对环境温度的交叉灵敏度较小。HLPG作为扭转传感器也显示出巨大潜力，其灵敏度高达0.198 nm/(rad/m)，可用于测量扭转方向。
