High-sensitivity dynamic distributed pressure sensing with frequency-scanning φ-OTDR

Area of Science:

• Optoelectronics
• Fiber Optic Sensing
• Metrology

Background:

• Distributed fiber optic sensing offers advantages for structural health monitoring and industrial process control.
• Traditional phase-sensitive optical time-domain reflectometry (φ-OTDR) systems face limitations in sensitivity and dynamic range for certain applications.
• Brillouin optical time-domain analysis (BOTDA) is a common technique but exhibits lower pressure sensitivity.

Purpose of the Study:

• To develop and demonstrate a high-sensitivity dynamic distributed pressure sensor.
• To leverage frequency-scanning φ-OTDR for enhanced pressure measurement capabilities.
• To achieve high sampling rates for capturing rapid pressure changes.

Main Methods:

• Implementation of a frequency-scanning phase-sensitive optical time-domain reflectometry (φ-OTDR) system.
• Utilization of an injection locking laser for multi-frequency signal generation via double-sideband modulation.
• Employing a single-mode fiber (SMF) as the sensing element.

Main Results:

• Achieved a high pressure sensitivity of 702.5 MHz/MPa in the SMF, approximately 1000 times greater than Brillouin optical time-domain analysis.
• Demonstrated a dynamic pressure experiment with rapid relief from 2 to 0 MPa.
• Attained a maximum sampling rate of 33.3 kHz over a 25-m SMF.
• Showcased a measurement uncertainty of 0.61 kPa for the proposed sensor scheme.

Conclusions:

• The proposed frequency-scanning φ-OTDR system offers a significant advancement in high-sensitivity dynamic distributed pressure sensing.
• The enhanced sensitivity and high sampling rate enable precise monitoring of rapid pressure fluctuations.
• This technology holds potential for critical applications requiring accurate and real-time pressure measurements.