High spatial resolution fast Brillouin optical time-domain analysis enabled by frequency-agility digital optical...

Area of Science:

• Fiber optic sensing
• Optical metrology
• Signal processing

Background:

• Brillouin optical time-domain analysis (BOTDA) is crucial for distributed fiber sensing.
• Existing BOTDA systems face limitations in achieving both high spatial and frequency resolution simultaneously.
• Digital optical frequency comb (DOFC) technology offers potential for advanced optical sensing applications.

Purpose of the Study:

• To propose and demonstrate a novel scheme for enhancing spatial resolution in fast BOTDA systems.
• To achieve high spatial resolution without sacrificing frequency resolution using DOFC probes.
• To improve the performance of BOTDA sensors for applications requiring fast and precise measurements.

Main Methods:

• Utilizing frequency-agility probes from a digital optical frequency comb (DOFC).
• Implementing frequency interleaving of multiple DOFC probes to retrieve Brillouin gain spectrum.
• Introducing quadratic phase coding to mitigate the high peak-to-average power ratio of probes.

Main Results:

• Achieved a record 5-m spatial resolution over a 10-km fiber.
• Maintained a frequency uncertainty of less than 2-MHz.
• Demonstrated a 1-GHz dynamic measurement range.
• Successfully performed 10-Hz vibration sensing at a 40-Hz sampling rate.

Conclusions:

• The proposed DOFC-based BOTDA scheme significantly enhances spatial resolution.
• The method enables high-frequency resolution retrieval and fast measurement capabilities.
• This advancement holds great potential for advanced fiber optic sensing and vibration analysis.