Miniaturized optical fiber Fabry-Perot interferometer fabricated by femtosecond laser irradiation and selective chemical etching

A U-shaped optical fiber inline microchannel was fabricated by femtosecond laser irradiation and subsequent selective chemical wet etching. A high quality micro-cavity embedded inside the channel was obtained to construct a Fabry-Perot interferometer (FPI). A fringe visibility of 20 dB in spectrum domain was achieved. High temperature survivability of this micro device was also demonstrated. The proposed assembly-free optical fiber inline interferometer is attractive for sensing applications in high-temperature harsh environments.