Magnetic field sensing using standard uniform FBGs

Area of Science:

• Physics
• Optical Engineering
• Materials Science

Background:

• Direct magnetic field sensing relies on the Faraday effect, inducing circular birefringence in optical fibers.
• Standard optical fibers exhibit intrinsic linear birefringence comparable to or exceeding Faraday-induced effects.
• Existing methods using fiber Bragg gratings (FBGs) often yield poor accuracy due to these birefringence challenges.

Purpose of the Study:

• To develop a more accurate magnetic field sensing method using optical fibers.
• To overcome the limitations of standard fiber Bragg grating (FBG) based magnetic field sensors.
• To establish a novel readout technique for enhanced magnetic field detection.

Main Methods:

• Utilizing the Faraday effect to induce circular birefringence in telecommunication-grade optical fibers.
• Employing fiber Bragg gratings (FBGs) in transmission mode for optical probing.
• Computing the Mueller matrix of the FBG to determine the rotation of the diattenuation vector.

Main Results:

• Demonstrated that the rotation of the diattenuation vector is a sensitive indicator of magnetic field evolution.
• Achieved a magnetic field resolution of 0.1 Tesla.
• Showcased the effectiveness of the Mueller matrix method for overcoming birefringence limitations.

Conclusions:

• The rotation of the diattenuation vector from an FBG's Mueller matrix offers an efficient readout for magnetic field sensing.
• This technique significantly improves upon traditional methods limited by intrinsic fiber birefringence.
• The developed approach provides a high-resolution (0.1T) solution for magnetic field detection without specialized materials.