Multicore fiber beacon system for reducing back-reflection in satellite quantum key distribution

Cameron Simmons, Ross J. Donaldson

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)
42 Downloads (Pure)


Optical beaconing is an important part of the acquisition, pointing and tracking system necessary for free-space quantum key distribution (QKD). However, uplink beacon back-reflections from the receiver architecture can result in noise. Wavelength- and time-division multiplexing has been used, but neither is yet sufficient to make back-reflection negligible. The use of additional telescopes increases complexity and pointing error. Here, we propose the use of a 2-by-2 multicore fiber, to act as an optical uplink beacon source. This spatially separates the QKD channel and optical uplink beacon. Up to 50 dB improvement in noise rejection over a purely spectrally divided system was demonstrated. The route to further improvements through greater fiber core separation is described. Beacon systems designed in this way could provide a combination of reduced complexity and improved noise performance to free-space and satellite QKD and optical communications.
Original languageEnglish
Pages (from-to)23382-23392
Number of pages11
JournalOptics Express
Issue number14
Early online date28 Jun 2023
Publication statusPublished - 3 Jul 2023


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