调相谱检测技术下谐振式光纤陀螺实验研究

谐振式光纤陀螺(R-FOG)是新一代光学传感器的代表.提出一种基于调相谱检测技术的R-FOG开环系统.作为核心敏感部件的谐振腔是由长度为5.5 m的保偏光纤和耦合系数为20%的保偏耦合器组成.谐振腔直径为0.1 m.根据测试其谐振曲线,得到该谐振腔的自由谱宽、半高全宽、清晰度以及谐振深度分别为35.7 MHz、2.21 MHz、16.2和0.95.由上述谐振腔参数计算得到该系统的极限灵敏度为4×10-7rad/s.利用声光调制器在R-FOG顺时针和逆时针光路中引入不同的频率差,用于等效陀螺转动引起的Sagnac频差,得到了陀螺的模拟开环响应曲线.根据得到的等效输出响应曲线,计算出该系统的动态范围可达 13.5 rad/s到-13.5 rad/s.由开环响应曲线中得到系统的检测灵敏度为0.03 rad/s;采取措施克服系统中的噪声源,可以进一步提高系统的检测灵敏度.

Experiments in PM-Spectroscopy Resonator Fiber Optic Gyro

Resonator fiber optic gyro (R-FOG) is a novel candidate for the next generation inertial rotation sensor. Using the phase modulation spectroscopy technique, an open-loop R-FOG system is proposed. The key part of the R-FOG is the resonator. It is composed of a 5.5m-length polarization maintaining fiber ring and a polarization maintaining fiber coupler with the coupling ratio 20%. The diameter of the resonator is 0.1m. Observed from the resonance curve, the free spectral range of the resonator (FSR), the full width at half maximum of the resonance curve (FWHM), the finesse of the resonator (F) and the resonance depth are 35.7MHz, 2.21MHz, 16.2, 0.95, respectively. According to these parameters of the resonator, it can be estimated that the shot-noise-limited sensitivity of this system will be 4×10-7rad/s. In the experiment, the frequency difference between the driving frequencies of the two AOMs is equivalent to the Sagnac frequency deviation caused by the gyro rotation. Due to this frequency difference, the equivalent gyro output signal is observed. From the gyro output curve, the gyro dynamic range is from +13.5rad/s to -13.5rad/s. From the equivalent gyro output, the detecting sensitivity of 0.03 rad/s is estimated. The detecting sensitivity can be increased by some countermeasures against the error sources.