Ultrastable Long-haul Fibre-optic Radio Frequency Transfer Based on PLL Frequency Mixing

Abstract

This paper presents the system for ultrastable radio frequency (RF) transfer over long-haul optical fiber link without any relay system. Signal to noise ratio of the phase conjugate signal is improved by 20 dB(@RBW 2 MHz) via utilising phase locked loop during the frequency mixing process. The experiments are performed over 1007 km fiber link, detailed information of which is given in this paper. The measured fractional frequency stability of 2.4 GHz RF signal transmission system approaches $8.20\times 10^{-14} @1\ \mathrm{s}$ and $7.87\times 10^{-17} @10000\ \mathrm{s}$.