We demonstrated an underwater frequency transfer technique with a green diode laser. The characteristic of the timing fluctuation and instability for the transfer technique was analyzed and simulated. With this technique, we had transferred a highly stable 100-MHz frequency signal over an underwater link with distances of 3 m, 6 m, and 9 m for 5000 s, respectively. The experimental results involving the underwater transfer of the 100-MHz radio-frequency signal shows that the rms timing fluctuations are 5.9 ps (3-m link), 6.4 ps (6-m link), and 8.4 ps (9-m link). The calculations also show that the relative Allan deviations for the 3-m, 6-m, and 9-m transmission links are 5.6 × 10−13 at 1 s and 5.3 × 10−15 at 1000 s, 5.8 × 10−13 at 1 s and 1.1 × 10−14 at 1000, and 6.8 × 10−13 at 1 s and 1.1 × 10−14 at 1000 s, respectively. The measured instabilities were lower than Rb and Cs atomic clocks, implying that the proposed frequency transfer scheme can potentially be used to transfer the signals of these atomic clocks over underwater links.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.