激光调制参数对光纤环型谐振腔光谱特性影响

谐振光学环型腔作为光学陀螺的核心敏感单元，其光学调制谱和与之对应的鉴频曲线的特性成为提高光学陀螺系统检测灵敏度的关键。为了研究光学陀螺的调制和鉴频谱线特性，优化陀螺性能，设计并搭建了实验测试系统，光纤环形谐振腔采用分光比为50∶50、直径17 cm的保偏光纤，总长2.2 m。使用直流高压放大器扫描窄线宽激光器（线宽小于1 kHz）的压电转化模块,扫描频率和电压分别选取20 Hz和1 V，使用模拟比例积分电路进行锁频并反馈给激光器的压电转化模块，使激光器的输出频率跟踪谐振腔实时变化。研究分析了光纤环型谐振腔在两种情况下所对应的透射谱和鉴频曲线:第一种情况为调制电压分别为2 V和4 V，对应调制频率从100 kHz到4 MHz变化；第二种情况为当调制频率为900 kHz，调制电压从2 V到10 V变化。通过实验，得到了不同调制参数下光学陀螺谱线的谐振深度、半高全宽、线性带宽、动态范围、品质因数、标度因数以及对应的锁频精度七种物理量的详细变化情况，并进一步得到了静态测试条件下三种陀螺的最佳调制频率及与之所匹配的调制电压。为进一步研究激光调制对光纤环型谐振腔光谱的影响提供指导。

Influence of spectral characteristics on fiber ring resonator by laser modulation parameters

The resonator fiber optic gyro will be the next-generation fiber-optic gyro following the interferometric fiber optic gyroscope due to its small size, high sensitivity, low power consumption, high reliability, and long life. As the core sensitive unit of resonator gyro, characteristics of transmission spectrum and the corresponding frequency discriminator curve in optical resonator become the key to improving the detection sensitivity of the optical gyro system. The experimental system is designed and built. The splitting ratio of the fiber coupler is 50:50. The fiber ring resonator is made by polarization maintaining fiber whose diameter and length are 17 cm and 2.2 m respectively. Piezoelectric transducer of narrow linewidth laser (linewidth is less than 1 kHz) is scanned by direct-current high voltage amplifier whose scanning frequency and voltage are 20 Hz and 1 V respectively. The analog circuit feedback system is adopted with proportional integral locking technique, so the output frequency of the laser can track the frequency of the resonator in real time. The transmission spectrum and discriminator curve of the fiber ring resonator are analyzed in two different cases. Firstly, the modulation voltages are 2 V and 4 V with a modulation frequency from 100 kHz to 4 MHz; Secondly, the modulation frequency is 900 kHz with a modulation voltage from 2 V to 10 V. Different varieties of seven parameters are obtained, such as the depth of resonance, the full width at half-maximum, the bandwidth, the dynamic range of linear zone, the quality factor, the scale factor and the precision of lock-in frequency. Moreover, three optimum modulation frequency and matched modulation voltage are obtained under static test conditions. These conclusions provide a guidance for further study on laser modulation effect on the spectrum of fiber ring resonators.