Modulation-free broadband fiber optic current sensor based on a linear resonant cavity

Area of Science:

• Optoelectronics
• Fiber optic sensing
• Electromagnetics

Background:

• Traditional current sensors often require active modulation, increasing complexity and cost.
• The Faraday effect in optical fibers provides a basis for non-invasive current sensing.
• Developing modulation-free sensors is crucial for simplifying instrumentation and reducing power consumption.

Purpose of the Study:

• To present a novel modulation-free, low-cost fiber optic current sensor.
• To investigate its performance for both direct current (DC) and alternating current (AC) measurements.
• To analyze the sensor's noise characteristics.

Main Methods:

• Utilized a broadband light source and a single-mode linear resonant cavity.
• Leveraged the Faraday effect to induce a phase difference in orthogonally polarized beams.
• Employed a 3x3 coupler and balanced photodetector for signal demodulation without active modulation.

Main Results:

• Achieved a sensitivity of 1.749 mV/A for DC measurements.
• Demonstrated a mean relative error below 0.2% within the 0-200 A range.
• Confirmed the sensor's capability for detecting alternating current and analyzed its noise performance.

Conclusions:

• The proposed fiber optic current sensor offers a cost-effective and modulation-free solution.
• It provides high accuracy for DC measurements and is suitable for AC detection.
• The sensor design is promising for practical current monitoring applications.