单轴Sagnac光纤干涉仪相位偏置控制

Phase Bias Control of Single Axis Optical Fiber Sagnac Interferometer

采用Sagnac光纤干涉仪的分布式光纤振动传感系统成本可大幅度降低。为了能够获得较好的信号响应灵敏度,必须对Sagnac光纤干涉仪进行相位偏置。介绍了一种单轴Sagnac光纤干涉仪相位偏置控制方案及其工作原理。从光脉冲接收机处获得传感光纤末端光反射器反射的光脉冲信号的幅度值,计算得到单轴Sagnac光纤干涉仪的静态相位值,然后调整、控制偏振控制器,将单轴Sagnac光纤干涉仪的静态相位偏置于0.5π±0.1,使得分布式光纤振动传感系统的小信号响应灵敏度改善10dB.

The cost of the distributed optical fiber vibration sensing system can be greatly reduced by using the optical fiber Sagnac interferometer.In order to obtain better signal response sensitivity,the phase bias of the optical fiber Sagnac interferometer must be performed.A phase bias control scheme and working principle of single axis optical fiber Sagnac interferometer are introduced.The optical pulse receiver acquired the amplitude of the optical pulse signals reflected from optical reflector which is placed at end of the sensing optical fiber.Then,CPU calculates the static phase value of single axis optical fiber Sagnac interferometer,controls and adjusts the polarization controller for putting the phase bias of single axis optical fiber Sagnac interferometer in 0.5π±0.1.The small signal response sensitivity of distributed optical fiber vibration sensing system is improved by 10 dB.