In-line fiber-optic Fabry-Perot ultrasound sensor formed by hollow-core photonic-crystal fiber

An in-line fiber-optic Fabry-Perot sensor formed by hollow-core photonic crystal fiber is used for ultrasound detection. The experimental results show that the wavelength-pressure sensitivity is ~7.29 times 10^-3 nm/MPa, which is about twice more than that of FBG.