Measurement of the impact of turbulence anisoplanatism on precision free-space optical time transfer

Abstract

Future free-space optical clock networks will require optical links for time and frequency transfer. In many potential realizations of these networks, these links will extend over long distances and will span moving platforms, e.g. ground-to-air or ground-to-satellite. In these cases, the transverse platform motion coupled with spatial variations in atmospheric optical turbulence will lead to a breakdown in the time-of-flight reciprocity upon which optical two-way time-frequency transfer is based. Here, we report experimental measurements of this effect by use of comb-based optical two-way time-frequency transfer over two spatially separated optical links. We find only a modest degradation in the time synchronization and frequency syntonization between two sites, in good agreement with theory. Based on this agreement, we can extrapolate this 2-km result to longer distances, finding only a few-femtosecond timing noise increase due to turbulence for a link from ground to a mid-earth orbit satellite.

References in corpus (7)

• Optical two-way time and frequency transfer over free space
• Synchronization of Distant Optical Clocks at the Femtosecond Level
• A coherent optical link through the turbulent atmosphere
• Comparing optical oscillators across the air to milliradians in phase and $10^{-17}$ in frequency
• Femtosecond Optical Two-Way Time-Frequency Transfer in the Presence of Motion
• Stabilized free-space optical frequency transfer
• Lasers for coherent optical satellite links with large dynamics

Cited by in corpus (11)

• 20 years of developments in optical frequency comb technology and applications
• 113 km Free-Space Time-Frequency Dissemination at the 19th Decimal Instability
• Quantum-limited optical time transfer for future geosynchronous links
• Femtosecond Synchronization of Optical Clocks Off of a Flying Quadcopter
• Point-to-Point Stabilised Optical Frequency Transfer with Active Optics
• Ultra-stable Free-Space Laser Links for a Global Network of Optical Atomic Clocks
• Femtosecond Optical Two-Way Time-Frequency Transfer in the Presence of Motion
• Optical Atomic Clock Comparison through Turbulent Air
• Methods for coherent optical Doppler orbitography
• Classical and Quantum Frequency Combs for Satellite-based Clock Synchronization
• Relativistic theory for time and frequency transfer through flowing media with an application to the atmosphere of Earth