Enhanced bandwidth distributed acoustic sensing using a frequency multiplexed pulse train and micro-machined point...

Area of Science:

• Optoelectronics
• Fiber optic sensing
• Acoustic detection

Background:

• Distributed Acoustic Sensing (DAS) traditionally faces limitations in bandwidth and noise.
• Existing interrogation systems often struggle with interference fading and limited spatial resolution.
• Micro-machined point reflectors offer potential for enhanced fiber optic sensing.

Purpose of the Study:

• To present an enhanced bandwidth distributed acoustic sensor (DAS).
• To improve the signal-to-noise ratio and spatial resolution of DAS systems.
• To demonstrate a scalable DAS approach for long-range sensing applications.

Main Methods:

• Utilized a frequency multiplexed interrogation system.
• Employed a micro-machined point reflector fiber with high reflectance (-48 dB).
• Increased the effective pulse repetition rate by a factor of 10.

Main Results:

• Achieved a phase noise as low as -101 dB (re rad²/Hz) over 2.5 km fiber.
• Obtained a strain noise of 0.095 pε/√Hz with 10 m spatial resolution.
• Demonstrated a 10-fold increase in sensor bandwidth without interference fading noise.
• Successfully performed sensing up to 10 km using 1000 point reflectors.

Conclusions:

• The proposed frequency multiplexed DAS with point reflectors significantly enhances sensor bandwidth and reduces phase noise.
• This approach offers a scalable solution for long-range, high-resolution acoustic sensing.
• The system overcomes limitations of traditional DAS, paving the way for advanced monitoring applications.