Bending sensor with enhanced sensitivity via parallel dual-fiber Fabry-Perot cavities

In this work, a method to enhance the sensitivity of bending measurement by using parallel dual -fiber FabryPerot (F -P) cavity structure is proposed. The sensor consists of two standard single -mode fibers (SMF) and a large diameter fiber (LDF) with a diameter of 150 mu m. The experimental results show that the sensor can respond to bending in different directions due to the direction recognition ability of the eccentric distribution of the two interference cavities. Importantly, the sensitivity of the sensor can be increased by one time by calculating the difference of the two interference wavelengths, up to 1524.2 nm/m- 1. This method retains the advantages of simple fabrication and low cost of fiber optic F -P sensors, and has the potential to be widely used in fiber optic interferometric sensors.