Sapphire-fiber-based intrinsic Fabry–Perot interferometer

A sapphire optical fiber intrinsic Fabry–Perot interferometric sensor is demonstrated. A length of multimode sapphire fiber that functions as a Fabry–Perot cavity is spliced to a silica single-mode fiber. The interferometric signals of this sensor are produced by the interference between the reflection from the silica–sapphire fiber splice and the reflection from the free end face of the sapphire fiber. This sensor has been demonstrated for temperature measurement. A resolution of 0.2°C has been obtained over a measurement range of 310°C to 976°C.