介绍了一种双锥型光纤倾角传感器, 传感器采用康宁SMF-28单模光纤, 在光纤上加工两个光纤锥。光束经过第一个光纤锥时, 纤芯内的部分基模光被激发为高阶的包层模, 和芯层模式光一起在光纤内传输, 到达第二个光纤锥时, 包层模重新耦合进入芯层, 并与芯层的基模光发生干涉, 由于纤芯内的基模与包层模的有效折射率存在差异, 从而引入相位差, 干涉谱强度随着波长呈现峰谷值变化。倾斜角变化时, 包层模的有效折射率也发生变化, 干涉谱强度的峰值和谷值均产生移动, 根据峰值或谷值的移动量, 即可测量相对应的倾斜角度。实验结果表明, 加工的光纤角度传感器能够有效的测量倾斜角度值, 两个方向上的测量精度可分别达到0.151 nm/°和0.087 nm/°。

An inclinometer based on dual tapered fiber is introduced. Corning single-mode fiber SMF-28 is used in the inclinometer. Two fiber tapers are fabricated in the fiber. When a light beam transmits through the first taper, high-order cladding modes are partially excited from the core mode. The cladding modes and the core mode propagate along the fiber together. When the light beam transmits through the second taper, the cladding modes are coupled into the core again and interfered with the core mode. As the effective refractive indexes of the core mode and the cladding modes are different, phase differences are introduced. The interference spectral intensity shows peaks and valleys at different wavelengths. As the effective refractive index of the cladding mode changes with the various of the tilt angle, the peaks and valleys of the interference spectral intensity will also shift. As a result, the tilt angle could be computed through the shift of a peak or a valley. Experimental results show that the tilt angle can be measured effectively with the fabricated fiber inclinometer. The accuracies for two directions are 0.151 nm/° and 0.087 nm/° respectively.