Precision Microwave Frequency Transfer over Dual Free-Space Optical Links
E.J. Adles, N.G. Bos, B.M. Cannon, M.L. Dennis, A.J. Goers, I.M. Hughes, J.C. Juarez, K.G. Petrillo, and J.L. Riggins, II, Johns Hopkins Applied Physics Laboratory
Location: Regency B
Date/Time: Thursday, Feb. 1, 3:05 p.m.
We have developed a complete system for the transfer of an X-band microwave reference frequency over two independent free-space optical links. The links use optical frequency combs, linear optical sampling, and two-way time transfer techniques to derive femtosecond precision correction signals for slaving two independent oscillators to a common remote reference oscillator. The differential phase noise of the remote slave oscillators is characterized to show low phase noise transfer of the master reference frequency within the loop bandwidth of the optical link.
System architecture will be described, and extensions for high-precision frequency and time transfer will be discussed. A unique feature of our architecture compared to previous approaches is that the precise time transfer is performed without a transfer comb, substantially reducing system complexity and cost. This architecture is easily extensible from point-to-point to point-to-multi-point configurations for future capabilities. Additionally, coarse time transfer is performed using a 10 Gbps layer 2 packet retransmission system developed for high speed free space laser communications. Thus, our system supports precise time transfer and simultaneous high-rate data communications for future applications.