A Magnetic Field Fiber Sensor Based on Side Hole Fiber Filled with Magnetic Fluid in Fiber Ring Laser Cavity

We proposed a simple magnetic field fiber sensor based on magnetic fluid (MF) filled side hole fiber (SHF) in fiber ring laser (FRL) system. The output wavelength of the laser shifts with the change of magnetic field, and its sensitivity is 0.4365 nm/mT at the range of 2 mT- 10 mT. Thanks to the high signal-to-noise ratio (SNR) and narrow linewidth of the laser cavity, its SNR is as high as 50 dB, and the 3-dB linewidth is 0.1 nm, without losing sensitivity. The designed sensor is expected to have potential applications in navigation system.