Solar-Blind Free-Space QKD Using Large-Core Fibers for Alignment-Tolerant Link Operation
- Author(s)
- Florian Honz, Winfried Boxleitner, Michael Hentschel, Philip Walther, Hannes Hübel, Bernhard Schrenk
- Abstract
While fiber-optic quantum key distribution (QKD) systems have reached a technological maturity that permits field deployments, the complexity of free-space optical (FSO) QKD systems introduced to ensure minimal coupling loss over air hinders the use of QKD in fiber-scarce environments. As a response to this challenge, we present a simplified approach that leverages large-core fibers at the receiving air interface of short-range terrestrial FSO links. We show that the increased sensitivity to solar irradiance, as it arises from the adoption of alignment-tolerant multi-mode fibers, can be effectively mitigated through a spectral E-band allocation of the QKD channel. We accomplish a secure-key rate of 869 b/s/detector for a 63-m long outdoor free-space link during day-light operation at 42.9 klux, despite employing a 25-μm core fiber at Bob's QKD receiver. We further demonstrate the co-existence of a classical data stream over the solar-blind FSO QKD link.
- Organisation(s)
- Quantum Optics, Quantum Nanophysics and Quantum Information
- External organisation(s)
- Austrian Institute of Technology
- Journal
- Journal of Lightwave Technology
- Volume
- 43
- Pages
- 7155-7162
- No. of pages
- 8
- ISSN
- 0733-8724
- DOI
- https://doi.org/10.1109/JLT.2025.3575204
- Publication date
- 08-2025
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 103025 Quantum mechanics, 103021 Optics
- Keywords
- ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics
- Portal url
- https://ucrisportal.univie.ac.at/en/publications/16d4da5a-6a10-458f-bbb1-03acba216bb4