Vibration immunity fiber optic current sensor employing a spun or twisted highly linear birefringence fiber

Fiber optic current sensors (FOCS) based on Faraday magneto-optical effect have plenty of privileges compared to the traditional current sensors. However, the residual linear birefringence and environmental vibration sensitive problem are the fatal drawback in Sagnac fiber optic current sensors. In this paper, a vibration immunity sensing loop with a function of passive fiber optic polarization control is proposed, which consist of a spun or twisted fiber with highly birefringence. A spun or twisted fiber possesses two crucial functions: remove the residual linear birefringence and control polarization of light. It is used as a substitute for fiber-optic quarter wave plate, which is sensitive to temperature fluctuation. Use the special fiber to encircle a distinctive geometric configuration, eliminating the influence of vibration or the Sagnac effect undesired. It has been demonstrated that the novel fiber optic current sensor has high sensitivity, considerable wide dynamic range, resistance to electromagnetic interference, and immunity of vibration.