A Short Range Two-way Frequency Transfer Experiment in Free Space

This paper introduces a short distance two-way frequency transfer experiment in free space. We carried out two-way frequency transfer experiments on 8 m free space link in the laboratory. When the integration time is 1s, the frequency stability of two-way frequency transfer is $1.43\times 10^{-15}$. When the integration time is 4000s, the frequency stability increases to $1.13\times 10^{-17}$. The frequency stability of two-way frequency transfer is higher than that of free space frequency transfer without compensation. This proves that two-way frequency transfer technology can passively offset the frequency fluctuations introduced by links.