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Sub-nanosecond optical underwater two-way time transfer using green semiconductor laser
Optics Express
|November 11, 2025
Summary
High-precision underwater time transfer was achieved using a green laser system. This optical technique enables sub-nanosecond synchronization for underwater applications.
Area of Science:
- Optical Physics
- Marine Technology
- Precision Measurement
Background:
- Accurate time transfer is crucial for various underwater applications, including navigation, communication, and scientific research.
- Existing methods for underwater time synchronization face challenges due to signal attenuation and environmental factors.
Purpose of the Study:
- To demonstrate a high-precision optical underwater two-way time transfer system.
- To achieve sub-nanosecond-level time transfer accuracy in an underwater environment.
Main Methods:
- Development of an underwater two-way time transfer system utilizing a green semiconductor laser.
- Conducting a time transfer experiment over a 6-meter underwater link.
Main Results:
- The system achieved a total root mean square (RMS) timing drift of approximately 345 picoseconds (ps) over 20,000 seconds.
- Time stability measurements showed a time deviation of 257 ps at a 1-second averaging time and 48 ps at a 1000-second averaging time.
Conclusions:
- The demonstrated optical technique enables sub-nanosecond underwater time transfer.
- This method provides critical support for developing advanced underwater sub-nanosecond synchronization systems.
