Extremely high sensitivity magnetic field sensing based on birefringence-induced dispersion turning point characteristics of microfiber coupler

A kind of ultrasensitive magnetic field sensor based on microfiber coupler and magnetic fluid (MF) is proposed and investigated. As the working wavelength is near the birefringence-induced dispersion turning point (B-DTP), the sensitivity has been enhanced considerably and the maximum sensitivity can achieve −97.856 nm/mT. By tracking the B-DTP, the problem of high sensitivity but narrow detection range can be solved. The temperature sensitivity of the structure is 0.816 nm/℃. The proposed sensor has the advantages of extremely high sensitivity, which has the potential applications in high-precision magnetic field measurement.