Research on the Dual Modulation of All-Fiber Optic Current Sensor

Area of Science:

• Optoelectronics
• Fiber optic sensing
• Instrumentation

Background:

• Traditional current sensors face limitations in precision and anti-interference capabilities.
• Developing advanced fiber optic sensors is crucial for accurate microcurrent measurements.
• Acousto-optic modulators (AOM) and electro-optical modulators (EOM) offer precise control over light properties.

Purpose of the Study:

• To develop and characterize an all-fiber current sensor (AFOCS) utilizing AOM and EOM with a pulsed light source.
• To investigate the impact of modulation parameters on sensor performance.
• To achieve high sensitivity, resolution, and a wide measurement range for microcurrents.

Main Methods:

• Utilizing AOM for pulsed light generation via amplitude modulation.
• Constructing a reflected interferometer with EOM for phase modulation and enhanced anti-interference.
• Employing a correlation demodulation algorithm for data processing.
• Conducting modeling and experimental analysis to determine the influence of AOM's modulation frequency and duty cycle.

Main Results:

• The AOM duty cycle significantly affects the normalized scale factor.
• AOM modulation frequency impacts correlation demodulation amplitude and signal-to-noise ratio.
• Optimizing the frequency multiplication factor between AOM and EOM minimizes ratio error to <1.8%.
• Achieved sensitivity of 0.01063 mV/mA and resolution of 3 mA.
• Demonstrated a wide measurement range from 11 mA to 196.62 A.

Conclusions:

• The developed all-fiber current sensor effectively measures microcurrents with high precision.
• Parameter optimization, particularly the AOM duty cycle and frequency multiplication factor, is key to sensor performance.
• The AFOCS meets practical requirements for microcurrent measurement applications.