Miniature all-fiber extrinsic Fabry–Pérot interferometric sensor for high-pressure sensing under high-temperature conditions

An extrinsic Fabry–Pérot interferometric (EFPI) sensor created at the tip of an optical fiber is presented for high-pressure measurement. The sensor, with a diameter of 125 µm, is fabricated exclusively in pure silica fiber, which makes it suitable for applications in high-temperature environments. The EFPI cavity of the sensor is formed by fusion splicing, cleaving, polishing, and femtosecond laser micromachining. Experimental studies show that the sensor exhibits high stability and good linearity over a pressure range of 10 MPa under high-temperature conditions (up to 800°C). This sensor offers great potential for use in high-temperature applications.