Guo Tuan, Liu Fu, Du Fa, Zhang Zhaochuan, Li Chunjie, Guan Bai-Ou, Albert Jacques
Institute of Photonics Technology, Jinan University, Guangzhou 510632, China.
Opt Express. 2013 Aug 12;21(16):19097-102. doi: 10.1364/OE.21.019097.
A compact fiber-optic vector rotation sensor in which a short section of polarization-maintaining (PM) fiber stub containing a straight fiber Bragg grating (FBG) is spliced to another single mode fiber without any lateral offset is proposed and experimentally demonstrated. Due to the intrinsic birefringence of the PM fiber, two well-defined resonances (i.e. orthogonally polarized FBG core modes) with wavelength separation of 0.5 nm have been achieved in reflection, and they exhibit a high sensitivity to fiber rotation. Both the orientation and the angle of rotation can be determined unambiguously via simple power detection of the relative amplitudes of the orthogonal core reflections. Meanwhile, instead of using a broadband source (BBS), the sensor is powered by a commercial vertical cavity surface emitting laser (VCSEL) with the laser wavelength matched to the PM-FBG core modes, which enables the sensor to work at much higher power levels (15 dB better than BBS). This improves the signal-to-noise ratio considerably (50 dB), and makes a demodulation filter unnecessary. Vector rotation measurement with a sensitivity of 0.09 dB/deg has been achieved via cost-effective single detector real time power measurement, and the unwanted power fluctuations and temperature perturbations can be effectively referenced out.
提出并通过实验证明了一种紧凑型光纤矢量旋转传感器，其中一段包含直光纤布拉格光栅（FBG）的保偏（PM）光纤短节被熔接到另一根单模光纤上，且没有任何横向偏移。由于保偏光纤的固有双折射，在反射中实现了两个清晰定义的共振（即正交偏振的FBG纤芯模式），波长间隔为0.5 nm，并且它们对光纤旋转表现出高灵敏度。通过简单地检测正交纤芯反射的相对幅度的功率，就可以明确确定旋转的方向和角度。同时，该传感器不是由宽带光源（BBS）供电，而是由商用垂直腔面发射激光器（VCSEL）供电，其激光波长与保偏光纤布拉格光栅纤芯模式匹配，这使得传感器能够在更高的功率水平下工作（比BBS高约15 dB）。这大大提高了信噪比（约50 dB），并且无需解调滤波器。通过经济高效的单探测器实时功率测量，实现了灵敏度为0.09 dB/deg的矢量旋转测量，并且可以有效地消除不必要的功率波动和温度扰动。
