High-sensitivity optical fiber magnetic field sensor based on multimode optical fiber multi Fabry-Perot interference...

Area of Science:

• Optoelectronics
• Fiber optics sensing
• Magnetometry

Background:

• Accurate measurement of weak magnetic fields is crucial for various scientific and industrial applications.
• Existing magnetic field sensors often face limitations in sensitivity, size, or operating environment.
• Optical fiber sensors offer advantages such as immunity to electromagnetic interference and remote sensing capabilities.

Purpose of the Study:

• To propose and demonstrate a high-sensitivity optical fiber magnetic field sensor.
• To investigate the performance of a multi-Fabry-Perot interference cavity in detecting weak magnetic fields.
• To explore the potential applications of the sensor in weak magnetic environments.

Main Methods:

• Fabrication of a multi-Fabry-Perot (F-P) interference cavity within an etched multimode optical fiber (MMF).
• The cavity structure consists of UV glue, magnetic fluid, and UV glue, forming a sandwich configuration.
• The sensor detects external magnetic fields by analyzing changes in the reflection spectra of the multi-F-P cavity, which are influenced by variations in the magnetic fluid's refractive index and cavity length.

Main Results:

• The sensor achieved a high magnetic field sensitivity of 299.7 pm/mT using wavelength demodulation.
• An intensity demodulation method yielded a sensitivity of 0.164 dB/mT.
• These results were obtained in the weak magnetic induction intensity range of 0–8 mT.

Conclusions:

• The proposed optical fiber sensor demonstrates high sensitivity for detecting weak magnetic fields.
• The sensor design, based on a multi-F-P cavity in an etched MMF with magnetic fluid, is effective for magnetic field measurement.
• The sensor holds potential for applications requiring precise magnetic field detection in weak magnetic environments.