Shen Fangcheng, Wang Changle, Sun Zhongyuan, Zhou Kaiming, Zhang Lin, Shu Xuewen
Opt Lett. 2017 Jan 15;42(2):199-202. doi: 10.1364/OL.42.000199.
We UV inscribe and characterize a long-period fiber grating with a period of 25 μm. A series of polarization-dependent dual-peak pairs can be seen in the transmission spectrum, even though only the symmetrical refractive index modification is introduced. The fabricated grating exhibits a lower temperature sensitivity compared with standard long-period gratings and an enhanced refractive index sensitivity of ∼312.5 nm/RIU averaged from 1.315 to 1.395, which is more than four-fold higher than standard long-period gratings in this range. The full width at half-maximum of the fabricated grating is only about 0.6 nm, allowing for high-resolution sensing. Moreover, the grating period is so small that the attenuation dip corresponding to a high-order Bragg resonance can also be seen, which can act as a monitor of the unwanted perturbation to realize dual-parameter sensing.
我们对周期为25μm的长周期光纤光栅进行紫外写入和表征。尽管仅引入了对称的折射率调制，但在透射光谱中仍可看到一系列与偏振相关的双峰对。与标准长周期光栅相比，所制备的光栅表现出较低的温度敏感性，并且在1.315至1.395范围内平均折射率灵敏度提高了约312.5 nm/RIU，比该范围内的标准长周期光栅高出四倍多。所制备光栅的半高宽仅约为0.6 nm，可实现高分辨率传感。此外，光栅周期非常小，以至于还可以看到对应于高阶布拉格共振的衰减凹陷，其可作为对有害扰动的监测器以实现双参数传感。
