LAUSR

Abstract. An inline fiber Mach–Zehnder interferometer (MZI) based on a cross-type microchannel in single mode–multimode–single mode fiber structure was proposed. The cross-type microchannel was fabricated in the fiber material directly using femtosecond laser-induced breakdown in water. The horizontal part of the cross-type microchannel along the fiber direction results in enough phase difference for the interference, and the cross-type shape makes the whole structure more robust because a smaller part of fiber material is etched. In addition, the proposed MZI shows high-pressure sensitivity (−14.27  nm  /  MPa), low-temperature cross sensitivity (0.043 nm/°C), and low strain force cross sensitivity (0.257 nm/N), which makes it a promising candidate for applications in gas pressure sensing field.