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Sensing within the OTDR dead-zone using a two-mode fiber.
Optics Letters
|June 2, 2020
Summary
This study introduces a novel optical time-domain reflectometer (OTDR) using two-mode fiber to eliminate dead-zones. This advancement enables accurate sensing of vibration events within previously undetectable fiber optic regions.
Area of Science:
- Optoelectronics
- Fiber Optics
- Sensing Technologies
Background:
- Optical time-domain reflectometry (OTDR) systems suffer from "dead-zones" that prevent sensing or diagnostics near the fiber's front facet.
- These dead-zones limit the effectiveness of OTDR in applications requiring continuous monitoring or fault detection.
Purpose of the Study:
- To develop an OTDR system capable of overcoming the inherent dead-zone limitations.
- To demonstrate accurate sensing of events within the dead-zone using a novel fiber optic approach.
Main Methods:
- Utilized a two-mode fiber (TMF) in conjunction with a photonic lantern.
- Implemented a technique where OTDR optical pulses are injected as the fundamental mode (${{\rm LP}_{{01}}}$).
- Collected Rayleigh scattering signals associated with higher-order modes for analysis.
Main Results:
- Successfully eliminated the dead-zone originating from the front facet of the optical fiber.
- Demonstrated accurate sensing of both the position and frequency of a vibration event located within the dead-zone.
- Validated the TMF-based OTDR as a viable solution for overcoming dead-zone limitations.
Conclusions:
- The proposed TMF-based OTDR effectively overcomes traditional dead-zone issues.
- This technology enables sensing capabilities in previously inaccessible regions of optical fibers.
- Paves the way for enhanced diagnostic and monitoring applications in fiber optics.
