Broadband optical time-domain reflectometry for security analysis of quantum key distribution
Phys. Rev. Applied 24, 014010 – Published 7 July, 2025
DOI: https://doi.org/10.1103/368v-t34p
Abstract
In this paper, we present a method for security analysis of Trojan-horse attacks (THAs) launched on a practical fiber-based quantum key distribution system across a wide spectral range. To achieve this, we use optical time-domain reflectometry (OTDR) for spectral reflectance analysis in the near-infrared range λ = 1100–1800 nm with centimeter-level resolution and a noise floor down to −80 dB. A total theoretical security analysis of the THA side channel considering the spectral reflectance and transmittance data over this spectral range is conducted. To the best of our knowledge, our OTDR setup and the corresponding results are the first of their kind to be obtained across a wide spectral range.
