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Cost-effective Φ-OTDR with laser phase noise mitigation using self-mixing interferometry.
Optics Express
|August 13, 2025
Summary
This study presents a cost-effective phase-sensitive optical time-domain reflectometry (Φ-OTDR) system using a standard semiconductor laser. It mitigates laser phase noise and achieves fading-free detection, reducing system costs.
Area of Science:
- Optoelectronics
- Fiber Optic Sensing
- Photonics
Background:
- Phase-sensitive optical time-domain reflectometry (Φ-OTDR) systems traditionally require expensive, ultra-narrow linewidth lasers (NLL).
- Laser phase noise significantly impacts Φ-OTDR system performance and cost.
- Conventional systems often necessitate online optical amplifiers, increasing complexity and expense.
Purpose of the Study:
- To propose and demonstrate a novel Φ-OTDR system mitigating laser phase noise.
- To achieve fading-free detection over extended distances using cost-effective components.
- To reduce the overall cost and complexity of Φ-OTDR systems.
Main Methods:
- Utilized self-mixing interferometry to counteract laser phase noise.
- Implemented a triple-frequency scheme for fading-free detection.
- Employed an inexpensive distributed feedback semiconductor laser (DFB-SL) with a 93 kHz linewidth.
Main Results:
- Successfully mitigated the noise floor by 8 to 22 dB over 35 km compared to conventional systems.
- Achieved fading-free detection over 10 km without an online erbium-doped optical fiber amplifier (EDFA).
- Demonstrated the feasibility of using a DFB-SL as a viable light source for Φ-OTDR.
Conclusions:
- The proposed Φ-OTDR scheme offers a practical solution to the laser phase noise bottleneck.
- Eliminates the need for narrow linewidth lasers and online amplifiers, significantly reducing costs.
- Paves the way for cost-effective Φ-OTDR systems and on-chip integration.
