Strain Sensor Using Optical Fiber Unsymmetrical F-P Cavity and the Characteristic Analysis

An intrinsic Fabry-Perot cavity consisted of different reflective mirrors is used in fiber-optical sensors for measuring the strain. The character of the unsymmetrical fiber-optical Fabry-Perot cavity and fiber-optic longitudinal stress-strain effect is analysed. The general theory and measurement method of strain are presented. A low fineness Fabry-Perot cavity is used to improve the linearity of optical fiber strain sensors. The result of experiment agrees well with the theory.