Abstract
A Sagnac interferometer based on the fiber-optic gyroscope requires two couplers to constitute a reciprocal optic system. In order to simplify the conventional minimum configuration, we have investigated a single-coupler interferometer with reciprocity using the self-coupling effect of light source. The proposed interferometer was applied to a vibration sensor for physical security technology. At many important facilities, fences with vibration sensors are installed along the boundary of the premises to prevent any intrusion. The optical fiber type is suitable for situations in which the vibration sensors need to be easily fixed to the fences, particularly around intricately shaped premises for monitoring a wide range of areas. The sensor's basic characteristics were compared with conventional and non-reciprocal types and its performance as a vibration sensor was verified. Since it enables the simplification of optical systems and assembly processes, the self-coupled optical pickup is effective in reducing the cost of optical fiber sensors.
