Multiple-access relay stations for long-haul fiber-optic radio frequency transfer

TL;DR

This paper demonstrates a novel long-haul RF transfer scheme using multiple-access relay stations (MARSs) with independent noise compensation, enabling scalable, ultra-long-distance fiber-optic RF transfer with high stability.

Contribution

It introduces a new MARS-based scheme with independent link noise compensation and models the impact of MARS position on system stability, advancing long-haul RF transfer technology.

Findings

Successfully transferred a 1 GHz signal over 260-280 km fiber links.

Achieved fractional frequency instability below 6×10^{-14} at 1 s.

Demonstrated system scalability with multiple MARSs.

Abstract

We report on the realization of a long-haul radio frequency (RF) transfer scheme by using multiple-access relay stations (MARSs). The proposed scheme with independent link noise compensation for each fiber sub-link effectively solves the limitation of compensation bandwidth for long-haul transfer. The MARS can have the capability to share the same modulated optical signal for the front and rear fiber sub-links, simplifying the configuration at the repeater station and enabling the transfer system to have the multiple-access capability. At the same time, we for the first time theoretically model the effect of the MARS position on the fractional frequency instability of the fiber-optic RF transfer, demonstrating that the MARS position has little effect on system's performance when the ratio of the front and rear fiber sub-links is around $1:1$. We experimentally demonstrate a 1 GHz signal transfer by using one MARS connecting 260 and 280 km fiber links with the fractional frequency instabilities of less than $5.9\times10^{-14}$ at 1 s and $8.5\times10^{-17}$ at 10,000 s at the remote site and of $5.6\times10^{-14}$ and $6.6\times10^{-17}$ at the integration times of 1 s and 10,000 s at the MARS. The proposed scalable technique can arbitrarily add the same MARSs in the fiber link, which has great potential in realizing ultra-long-haul RF transfer.