Relative error's quadratic dependence on the electric current and the methods for its compensation in fiber optic...

Area of Science:

• Optoelectronics
• Sensor Technology
• Materials Science

Background:

• Fiber optic current sensors (FOCS) are crucial for high-current measurements.
• Existing FOCS exhibit unacceptable quadratic relative error escalation (REE) for direct current (DC) above 100 kA.
• This inaccuracy stems primarily from residual linear birefringence in spun fibers.

Purpose of the Study:

• To analytically and experimentally investigate the origin of REE in FOCS.
• To develop and demonstrate a compensation scheme to mitigate REE.
• To enhance the accuracy of FOCS for large DC measurements.

Main Methods:

• Analytical derivation of the relationship between REE and fiber birefringence.
• Experimental measurement of residual linear and circular birefringence in spun fibers.
• Implementation of a compensation scheme utilizing measured birefringence values.

Main Results:

• The REE of FOCS increases quadratically with measured DC, limiting accuracy.
• A compensation scheme reduced REE from -1.22% to -0.15% at 200 kA DC.
• Further reduction to -0.02% at 200 kA DC was achieved by experimentally determining the quadratic REE-current relation.

Conclusions:

• Residual linear birefringence is the primary cause of REE in FOCS at high currents.
• A novel compensation strategy effectively minimizes REE by accounting for fiber birefringence.
• This research offers a pathway to significantly improve FOCS accuracy for high-current sensing applications.