A novel long-period fiber grating (LPFG) with arc grid having chirped radius is proposed and fabricated by CO ₂ -laser writing. The radius of arc grid in this LPFG is linearly chirped along the light transmission direction, which provides a gradually changed refractive index modulation (RIM) higher than that of conventional planar grid, and causes multiple spectral dips corresponding different coupling process. Two spectral dips of the radius-chirped LPFG shows opposite shifting directions to the same bending direction, but the same direction in the heating process. Due to the gap distance between the two oppositely shifted dips, the bending sensitivity reaches as high as 12.67 nm/ $\text{m}^{-1}$ , and the temperature effect can be self-compensated. This structure has potential to be applied in building, machine and ground monitoring.

中文翻译：

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高频CO钪激光刻写弧半径啁啾长周期光纤光栅


提出并采用CO ₂激光刻写技术制作了一种新型长周期光纤光栅（LPFG），其具有啁啾半径的弧形栅格。该长周期光栅中的弧形栅格半径沿光传输方向线性啁啾，提供了比传统平面栅格更高的渐变折射率调制（RIM），并导致对应不同耦合过程的多个光谱凹陷。半径啁啾长周期光栅的两个谱谷显示出与相同弯曲方向相反的偏移方向，但在加热过程中方向相同。由于两个相反移动的倾角之间的间隙距离，弯曲灵敏度高达12.67 nm/ $\text{m}^{-1}$ ，并且温度效应可以自我补偿。这种结构有潜力应用于建筑、机器和地面监测。