Magnetic field and gas pressure sensor based on Mach–Zehnder interferometer with micro-groove fabricated by femtosecond laser pulse

Abstract

A microgroove type Mach–Zehnder interferometer (MZI) for gas pressure and magnetic field measurements was prepared using a femtosecond laser pulse in a single mode fiber. Due to the interference light passing through the microgroove, changing the refractive index (RI) of the medium in the microgroove will change the optical path difference between the two channels, leading to significant drift of the MZI transmission spectrum, thus achieving the measurement of environmental parameters. When the gas pressure inside the microgroove changes, the RI of the air changes, achieving the measurement of environmental gas pressure. When the microgroove is filled with magnetic fluid, changes in the environmental magnetic field will cause changes in the RI of the magnetic fluid, thus achieving measurement of the magnetic field. The experimental results show that the gas pressure sensitivity of the sensor is −5.03 nm/MPa, and the temperature cross-sensitivity is only 1.31 kPa/°C. This sensor achieves a magnetic field sensitivity of −0.3505 nm/mT in the magnetic field range of 6.4–13.6 mT. The sensor is small in size and easy to manufacture, making it a good choice for measuring air pressure and magnetic field.