基于光学微腔模式劈裂的角速率测量方法

Angular rate sensing based on mode splitting in an optical microresonator

传统的光学谐振陀螺(ROG)把背向散射作为重要误差源之一,须尽量抑制其影响.在光学谐振腔的品质因数极高时,背散光得到足够的增强,不能再被简单地视为噪声.背向散射会引发模式劈裂,所形成的劈裂模谐振频率会随腔体旋转角速率发生变化.结合Sagnac效应,修正有源光学谐振腔模式劈裂传感原理的数学模型,推导出腔体旋转角速率与劈裂值的映射关系式.通过仿真分析不同掺杂增益系数以及不同光纤锥耦合强度下的反射谱线,发现谐振腔工作在欠耦合区域更适合角速率测量.掺杂增益介质可以提高品质因数,减小谐振峰线宽,使得模式劈裂谱线更容易观测.理论与计算机仿真分析表明品质因数为108的光学微腔测量分辨率可达10-6(°)/s,所提出的角速率敏感机制很有应用前景.

Backscattering has been treated as one of the major error sources in resonant optic gyroscopes （ROG） in a traditional way, which has to be restrained. A microresonator with ultra-high quality factor can greatly enhance the backscattering light. As a result, it cannot be deemed as a disturbance noise anymore. Coupling of the scattering light and the original propagating light can induce mode splitting. The frequencies of the split modes change along with the angular rotation rate of the microresonator. Considering the Sagnac effect, the model that describes mode splitting in an active optical microresonator was modified and the explicit expression of angular rotation rate versus the splitting amount was derived. The resonator is preferred to work in the under-coupling regime by monitoring the reflection spectra at several excitation levels and taper fiber coupling conditions. Optical gain of the active medium can be utilized to manipulate the splitting profiles and to narrow the line widths, which helps the rate measurement. Theoretical analysis and simulation results show that the resolving power can reach 10^-6（ °）/s in a microresonator with a quality factor of l0s, providing a promising angular rate sensing mechanism.