Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Optica Laser Congress (ASSL, LAC, LS&C)

Performance analysis of optical free-space two-way time-frequency transfer

Fabrizio R. Giorgetta, William C. Swann, Laura C. Sinclair, Esther Baumann, Ian R. Coddington, Nathan R. Newbury

Published Jan 1, 2013• 1 citation
Publisher

Abstract

Optical free-space time-frequency transfer could support precisions and accuracy well beyond microwave-based transfer. We discuss the potential performance and its limitations based on a recent demonstration over a 2-km link that achieved residual instability < 10−18.
DOI
10.1364/lsc.2013.lm2b.4

Related papers

Time-Frequency Transfer through a 70 dB Free Space Channel: Towards Satellite-Ground Time Dissemination

Qi Shen, Jian-Yu Guan, Ting Zeng +15 more

Time and frequency transfer lies at the heart of the field of metrology. Compared to current microwave dissemination such as GPS, optical domain dissemination can provide more than one order of magnitude in terms of higher accuracy, which allows for many applications such as the redefinition of the second, tests of general relativity and fundamental quantum physics, precision navigation and quantum communication. Although optical frequency transfer has been demonstrated over thousand kilometers fiber lines, intercontinental time comparison and synchronization still requires satellite free space optical time and frequency transfer. Quite a few pioneering free space optical time and frequency experiments have been implemented at the distance of tens kilometers at ground level. However, there exists no detailed analysis or ground test to prove the feasibility of satellite-based optical time-frequency transfer. Here, we analyze the possibility of this system and then provide the first-step ground test with high channel loss. We demonstrate the optical frequency transfer with an instability of $10^{-18}$ level in 8,000 seconds across a 16-km free space channel with a loss of up to 70~dB, which is comparable with the loss of a satellite-ground link at medium earth orbit (MEO) and geostationary earth orbit (GEO).

arXiv:2003.08322•Mar 18, 2020•0 citations

Stabilized Free-Space Optical Frequency Transfer

David R. Gozzard, Sascha Schediwy, B. Stone +2 more

High-precision optical frequency transfer through free-space links will enable advances in fields ranging from coherent optical communication and satellite Doppler ranging, to tests of general relativity and fundamental physics. Previous work has focused on two-way time and frequency transfer techniques using optical frequency combs. Here the authors show that a continuous-wave coherent link can exceed the fractional frequency stability of frequency-comb methods by an order of magnitude. They also highlight and discuss the technical hurdles to implementing similar links over the distances required to reach low Earth orbit.

arXiv:1806.00945•Physical Review Applied•Aug 29, 2018•49 citations

Synchronization of distant optical clocks across free-space optical links

Nathan R. Newbury, Laura C. Sinclair, Hugo Bergeron +6 more

The continued remarkable advances in optical clocks and oscillators has led to a parallel strong development of optical clock networks [1]. Such networks have the potential to support a wide range of applications from basic time/frequency dissemination, to clock-based geodesy, to tests of general relativity [1]. To support optical clocks/oscillators at their highest accuracy and precision, these networks must rely on optical signals between the nodes to carry the timing signals. Networks based on the reciprocal transmission across fiber optics have allowed frequency comparisons between remote clocks across Europe and Japan [2, 3]. However, there are many potential applications, both terrestrial and space-based, for which the clocks will not be connected via an optical fiber and the signals must be sent across free space optical links. To this end, we have been developing techniques for the free-space transfer of time and frequency [4-6]. Moreover, rather than pursuing only frequency comparison, we have developed an approach that allows time comparison and even real-time synchronization between nodes. Such a capability can support the wide variety of proposed applications of mobile optical clock networks.

Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)•Jun 1, 2017•0 citations

Long-haul Transfer of Optical Frequencies in Free Space

Hyun Jay Kang, Jaewon Yang, Young‐Jin Kim +1 more

We report experimental results of concurrent transfer of multiple optical frequencies, coherently generated from an optical frequency comb, over an 18 km free-space link with real-time compensation of atmospheric phase noise.

Conference on Lasers and Electro-Optics•Jan 1, 2019•0 citations

Free-space dissemination of time and frequency with 10−19 instability over 113 km

Qi Shen, Jian-Yu Guan, Ji-Gang Ren +28 more

Abstract Optical clock networks play important roles in various fields, such as precise navigation, redefinition of “second” unit, and gravitational tests. To establish a global-scale optical clock network, it is essential to disseminate time and frequency with a stability of 10^−19 over a long-distance free-space link. However, such attempts were limited to dozens of kilometers in mirror-folded configuration. Here, we take a crucial step toward future satellite-based time-frequency disseminations. By developing the key technologies, including high-power frequency combs, high-stability and high-efficiency optical transceiver systems, and efficient linear optical sampling, we demonstrate free-space time-frequency dissemination over two independent links with femtosecond time deviation, 3 × 10−19 at 10,000 s residual instability and 1.6 × 10^−20 ± 4.3 × 10^−19 offset. This level of the stability retains for an increased channel loss up to 89 dB. Our work can not only be directly used in ground-based application, but also firmly laid the groundwork for future satellite time-frequency dissemination.

arXiv:2203.11272•Nature•Oct 5, 2022•138 citations

Unidirectional two-way optical frequency comparison and its fundamental limitations

Dan Xu, Olivier Lopez, Anne Amy‐Klein +1 more

High-quality frequency transfer based on existing telecommunication fiber links allows state-of-the-art microwave and optical clocks to be compared on a continental and potentially even intercontinental scale. We present a half-a-year-long data set of unidirectional optical frequency transfer over a 2 × 43 k m urban fiber link. We observe a relative frequency instability of 8.0 × 10 − 16 at 1 s and at best 6.0 × 10 − 18 at 10 6 s integration time. Our results show that the unidirectional two-way method gives the possibility to perform comparisons of international primary standards over fiber links faster than over satellite links. Moreover, we investigate the major limiting factors of such a unidirectional setup.

Optics Letters•Oct 5, 2020•8 citations
Time and frequency transfer lies at the heart of the field of metrology. Compared to current microwave dissemination such as GPS, optical domain dissemination can provide more than one order of magnitude in terms of higher accuracy, which allows for many applications such as the redefinition of the second, tests of general relativity and fundamental quantum physics, precision navigation and quantum communication. Although optical frequency transfer has been demonstrated over thousand kilometers fiber lines, intercontinental time comparison and synchronization still requires satellite free space optical time and frequency transfer. Quite a few pioneering free space optical time and frequency experiments have been implemented at the distance of tens kilometers at ground level. However, there exists no detailed analysis or ground test to prove the feasibility of satellite-based optical time-frequency transfer. Here, we analyze the possibility of this system and then provide the first-step ground test with high channel loss. We demonstrate the optical frequency transfer with an instability of 10−1810^{-18}10−18 level in 8,000 seconds across a 16-km free space channel with a loss of up to 70~dB, which is comparable with the loss of a satellite-ground link at medium earth orbit (MEO) and geostationary earth orbit (GEO).
High-precision optical frequency transfer through free-space links will enable advances in fields ranging from coherent optical communication and satellite Doppler ranging, to tests of general relativity and fundamental physics. Previous work has focused on two-way time and frequency transfer techniques using optical frequency combs. Here the authors show that a continuous-wave coherent link can exceed the fractional frequency stability of frequency-comb methods by an order of magnitude. They also highlight and discuss the technical hurdles to implementing similar links over the distances required to reach low Earth orbit.
The continued remarkable advances in optical clocks and oscillators has led to a parallel strong development of optical clock networks [1]. Such networks have the potential to support a wide range of applications from basic time/frequency dissemination, to clock-based geodesy, to tests of general relativity [1]. To support optical clocks/oscillators at their highest accuracy and precision, these networks must rely on optical signals between the nodes to carry the timing signals. Networks based on the reciprocal transmission across fiber optics have allowed frequency comparisons between remote clocks across Europe and Japan [2, 3]. However, there are many potential applications, both terrestrial and space-based, for which the clocks will not be connected via an optical fiber and the signals must be sent across free space optical links. To this end, we have been developing techniques for the free-space transfer of time and frequency [4-6]. Moreover, rather than pursuing only frequency comparison, we have developed an approach that allows time comparison and even real-time synchronization between nodes. Such a capability can support the wide variety of proposed applications of mobile optical clock networks.
Abstract Optical clock networks play important roles in various fields, such as precise navigation, redefinition of “second” unit, and gravitational tests. To establish a global-scale optical clock network, it is essential to disseminate time and frequency with a stability of 10^−19 over a long-distance free-space link. However, such attempts were limited to dozens of kilometers in mirror-folded configuration. Here, we take a crucial step toward future satellite-based time-frequency disseminations. By developing the key technologies, including high-power frequency combs, high-stability and high-efficiency optical transceiver systems, and efficient linear optical sampling, we demonstrate free-space time-frequency dissemination over two independent links with femtosecond time deviation, 3 × 10−19 at 10,000 s residual instability and 1.6 × 10^−20 ± 4.3 × 10^−19 offset. This level of the stability retains for an increased channel loss up to 89 dB. Our work can not only be directly used in ground-based application, but also firmly laid the groundwork for future satellite time-frequency dissemination.
High-quality frequency transfer based on existing telecommunication fiber links allows state-of-the-art microwave and optical clocks to be compared on a continental and potentially even intercontinental scale. We present a half-a-year-long data set of unidirectional optical frequency transfer over a 2 × 43 k m urban fiber link. We observe a relative frequency instability of 8.0 × 10 − 16 at 1 s and at best 6.0 × 10 − 18 at 10 6 s integration time. Our results show that the unidirectional two-way method gives the possibility to perform comparisons of international primary standards over fiber links faster than over satellite links. Moreover, we investigate the major limiting factors of such a unidirectional setup.