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Doppler-stabilized fiber link with 6 dB noise improvement below the classical limit
Optics Letters
|February 14, 2015
Summary
A new post-processing method improves ultrastable frequency dissemination over optical fiber by overcoming delay-unsuppressed noise. This technique achieves a 6 dB improvement, enhancing precision in frequency dissemination systems.
Area of Science:
- Physics
- Optical Communications
- Metrology
Background:
- Temperature variations and acoustic noise introduce phase noise in optical fiber frequency dissemination.
- Active stabilization techniques partially mitigate fiber-induced phase noise.
- Link performance is ultimately limited by delay-unsuppressed noise, related to light propagation delay.
Purpose of the Study:
- To demonstrate a post-processing approach to overcome the limitations of delay-unsuppressed noise.
- To improve the performance of ultrastable frequency dissemination along optical fiber links.
Main Methods:
- Implementing a subtraction algorithm between the remote optical signal and the round-trip signal.
- Utilizing experimental data from a 47 km metropolitan fiber link for validation.
Main Results:
- Achieved a 6 dB improvement in performance beyond the delay-unsuppressed noise limit.
- Experimental data confirmed the predicted performance enhancement.
- Demonstrated the effectiveness of the post-processing subtraction algorithm.
Conclusions:
- The proposed post-processing method effectively overcomes delay-unsuppressed noise in optical fiber frequency dissemination.
- This technique offers a significant performance enhancement for ultrastable frequency dissemination.
- The method is suitable for extending to various frequency dissemination applications.
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