Inner air-cavity based fiber in-line Mach-Zehnder interferometer fabricated by femtosecond laser and fusion splicing

摘要

We demonstrate a miniaturized fiber in-line Mach-Zehnder interferometer high-temperature sensor based on inner air-cavity adjacent to the fiber core, fabricated by femto-second laser micromachining and fusion splicing technique. Such a device is robust and insensitive to ambient refractive index change, with high temperature sensitivity of ～43.2 pm/°C, up to 1000°C,while exhibiting low cross-sensitivity to strain.