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Modified in-line Sagnac interferometer with passive demodulation technique for environmental immunity of a
1Institute of Electrical Engineering, National Sun Yat-Sen University, Kaohsiung, Taiwan.
Applied Optics
|March 6, 2008
Summary
A novel fiber-optic current sensor (FOCS) uses a modified Sagnac interferometer and passive demodulation to resist environmental vibrations. This fiber optic sensor achieves high sensitivity and immunity, making it suitable for power line monitoring.
Area of Science:
- Optoelectronics
- Fiber Optics
- Sensor Technology
Background:
- Fiber-optic current sensors (FOCS) are susceptible to environmental perturbations like vibrations.
- Conventional interferometers struggle to maintain performance under dynamic conditions.
Purpose of the Study:
- To develop a fiber-optic current sensor (FOCS) with enhanced immunity to environmental disturbances.
- To improve the demodulation linearity and sensitivity of FOCS in dynamic environments.
Main Methods:
- Implementation of a modified in-line Sagnac interferometer (MISI).
- Integration of a passive demodulation technique (PDT) for signal processing.
- Testing under simulated environmental perturbations, including vibrations up to 12 g acceleration.
Main Results:
- The MISI demonstrated significant noise floor suppression (20 dB) compared to conventional interferometers.
- The PDT ensured good linear demodulation with distortion rates below 0.9% in dynamic environments.
- Consistent high sensitivity of approximately 4.5 microrad/(A(rms) turns) was observed in both static and dynamic conditions.
Conclusions:
- The proposed MISI with PDT offers robust environmental immunity and high sensitivity for FOCS.
- The technology shows promise for reliable field-monitoring applications in power delivery lines.
- This advancement addresses key challenges in deploying fiber optic sensors in harsh environments.
