Precision millimeter-wave time transfer
Abstract
The exceptional level of accuracy (10^-18) of state of the art optical clocks holds great potential to advance capabilities in PNT, advanced communications, arrayed sensing networks, and basic science. However, unlocking this potential necessitates the development of synchronization and time-transfer techniques that can maintain the inherent stability and accuracy of remote optical clocks. GPS and two-way RF links can only provide accuracies at the ~50 ps to 1 ns level, lagging 5 to 6 orders of magnitude behind the inherent accuracy of optical clocks. Although free-space optical two-way time transfer has demonstrated subfemtosecond accuracy, the use of optical carriers requires strict line-of-sight operation, active tracking control as well as favorable weather conditions, which limits the deployment of this technique in real scenarios. Here we propose the use of mm-wave carriers for two-way time transfer as a trade-off between time accuracy and robustness against poor visibility or weather conditions, while also providing time broadcasting capabilities. This will be accomplished by direct downconversion of the optical clock to mm-wave carriers in the 75 GHz - 110 GHz range via optical frequency division techniques with optical frequency combs. The mm-waves inherit the stability of the optical clock, enabling us to achieve link accuracies at the level of 10 ps to 100 ps. A phase-stabilized bidirectional mm-wave frequency transfer link will be established in the lab between two sites, and then time information will be transfered via modulation of the mm-wave carrier using low-jitter software-defined-radio-based electronics. We will also explore direct modulation of the mm-wave carrier with clock-level optical frequency comb pulses as well as multiple mm-wave carrier techniques to reduce the requirements for low-jitter electronics. Finally, we will evaluate the feasibility of deploying a 1.5 km open air mm-wave link between NIST and CU-Boulder Engineering.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Feb 06, 2025
- Source ID
- FA95502410200
Entities
People
- Gabriel Santamaria Botello
Organizations
- Air Force Office of Scientific Research
- Colorado School of Mines
- United States Air Force