A new Mach-Zehnder interferometer in a thinned-cladding fiber fabricated by electric arc for high sensitivity refractive index sensing

This study proposes an inline electric-arc induced Mach-Zehnder interferometer (MZI) in a thinned cladding fiber. The proposed MZI is used for refractive index (RI) sensing. At the diameter of 56 μm and the length of 18 mm, in the RI of 1.3348–1.3558, the sensitivity is ∼580 nm/RIU, that is about 20 times greater than those of taper-based MZI sensors. Temperature characteristics of the MZI are investigated in 50–800 °C. It is demonstrated that the proposed MZI is a good choice for high-temperature harsh environment sensing.

► An inline electric-arc induced Mach-Zehnder interferometer (MZI) in a thinned cladding fiber is proposed.
► The refractive index sensitivity is significantly improved through thinned cladding fibers.
► A maximum sensitivity of ∼580 nm/RIU is obtained, that is ∼20 times greater than those measured by taper-based MZI sensors.
► Temperature characteristics of the MZI are investigated in 50–800 °C.
► The proposed MZI is a good choice for high-temperature harsh environment sensing.