Microwave-photonic low-coherence interferometry for dark zone free distributed optical fiber sensing

Area of Science:

• Optoelectronics and Photonics
• Fiber Optic Sensing Technology
• Microwave Photonics

Background:

• Distributed optical fiber sensing is crucial for structural health monitoring.
• Existing methods often suffer from limitations in spatial resolution or continuous coverage.
• Integrating microwave and photonic technologies offers potential for enhanced sensing capabilities.

Purpose of the Study:

• To propose and demonstrate a novel microwave-photonic low-coherence interferometry (MPLCI) system.
• To achieve fully distributed, dark-zone-free (spatially continuous) measurement in optical fibers.
• To combine high sensitivity and high spatial resolution in a single sensing system.

Main Methods:

• Utilized an unbalanced Michelson interferometer with a low-coherence laser source.
• Interrogated cascaded Fabry-Perot interferometers embedded within an optical fiber.
• Leveraged the synergistic advantages of microwave and photonic signal processing.

Main Results:

• Demonstrated a spatially continuous (dark-zone-free) distributed measurement capability.
• Achieved a high strain resolution of 95 nanostrain (nε).
• Confirmed a spatial resolution of 10 centimeters (cm).

Conclusions:

• The proposed MPLCI system effectively integrates microwave and photonic principles for advanced fiber sensing.
• The system achieves both high sensitivity and high spatial resolution, overcoming limitations of previous methods.
• MPLCI shows significant promise for demanding distributed sensing applications requiring precise measurements.