Microcavity strain sensor for high temperature applications

A microcavity extrinsic Fabry-Perot interferometric (EFPI) fiber-optic sensor is presented for measurement of strain. The EFPI sensor is fabricated by micromachining a cavity on the tip of a standard single-mode fiber with a femtosecond (fs) laser and is then self-enclosed by fusion splicing another piece of single-mode fiber. The fs-laser-based fabrication makes the sensor thermally stable to sustain temperatures as high as 800°C. The sensor exhibits linear performance for a range up to 3700 μ e and a low temperature sensitivity of only 0.59 pm/°C through 800°C.