Study of an Ultrahigh-sensitivity Coupling Fiber-optic Strain Sensor

One important characteristic of an optical fiber coupler is that its ratio of output power is sensitive to the length of the coupling zone. This character be used for precision strain sensing in this paper, in which the theory analysis and experimental scheme for such sensing applications are presented. The influences of environmental temperature and transversal strain are described in detail. Experimental results indicate that the fused biconical-tapered coupler is not only sensitive to strain but also exhibits a broad-ranged linear and monotonous relationship between strain and the output power ratio. Its excellent temperature stability and immune to transversal mechanical disturbance, making the fused biconical-tapered coupler an ideal candidate for a simple but highly effective optical fiber strain sensor.