Beamshaping beacon light for satellite quantum key distribution: Spatial separation and point ahead angle

Cameron Simmons*, Ross Donaldson

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contribution

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Quantum key distribution (QKD) uses quantum states in an optical channel to grow a key with guaranteed security. Satellite QKD (SatQKD) is a proposed topology for QKD which provides unlimited terrestrial range for links and allows mobile access. SatQKD (and generally satellite optical communications) optical ground stations (OGSs) require an optical beacon, a beam from OGS to satellite to assist pointing the satellite’s telescope(s). Beaconing is challenging for SatQKD due to the single-photon sensitivity of the receiver to back-reflected beacon light and the need to point the outgoing beacon ahead of the downlink channel (the point-ahead angle (PAA)). Hence, beacon light is often propagated through separate telescopes, increasing complexity. We describe a spatially separated beacon which reduces back-reflection errors and how its PAA is achieved. The far field beams of this and other beacon architectures are compared. Beaconing in this way can give greater up-time (due to less maintenance) and a lower cost barrier to development. A related system could have similar benefits for laser-guide-star telescopes.

Original languageEnglish
Title of host publicationQuantum Technology
Subtitle of host publicationDriving Commercialisation of an Enabling Science IV
EditorsMiles J. Padgett, Alessandro Fedrizzi, Michael Holynski, Alberto Politi
ISBN (Electronic)9781510668430
Publication statusPublished - 30 Nov 2023
EventSPIE Photonex 2023 - Glasgow, United Kingdom
Duration: 24 Oct 202327 Oct 2023

Publication series

NameProceedings of SPIE
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X


ConferenceSPIE Photonex 2023
Country/TerritoryUnited Kingdom


  • Beacon
  • Point-ahead
  • Quantum Key Distribution
  • Satellite

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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