Fabry-Perot Cavity-Based Optical Fiber Pressure Sensor

Abstract

An optical fiber sensor based on Fabry-Perot cavity is introduced; the Fabry-Perot cavity was fabricated by two collimated fibers with smooth end surfaces. The reflection spectrum of the Fabry-Perot cavity can be changed with the ambient pressure, and the reflection spectrum can be transferred into cavity length; thus, the cavity length can be measured to achieve the sensing of the ambient pressure. For the multi-beam interference of the Fabry-Perot cavity, the reflection spectrum was uniform waves with distinctive peaks and valleys. After the Fabry-Perot cavity was well encapsulated with metal structures, the fiber sensor can withstand high temperature of 150 °C and measure the pressure because the cavity length can be linearly varied with the surrounding pressure and the linear coefficient can be 0.99999. When the Fabry-Perot cavity-based sensor was suffered from the upward and downward pressure from 0 to 71 MPa, the cavity lengths of upward and downward were varied within 15 nm which was equivalent of 0.04 MPa. The repeatability and return difference of the sensor have also been studied and the parameters both verified the good property of this kind of sensor. An optical fiber sensor based on Fabry-Perot cavity is introduced, and the response of the cavity length to the ambient pressure, the repeatability, and return difference of the sensor have been studied.