Modular adaptive optics solution for a QKD receiver on a fork mount telescope system

Quantum key distribution (QKD) is a promising field within telecommunication and cryptography. QKD allows two parties to generate a shared secret key, which only the two communicating parties know, and can later be used to encrypt and decrypt messages. This leads to unbreakable data transmission. QKD was experimentally already tested on a Chinese mission called MICIUS. Future QKD protocols may also benefit from coupling into an optical single-mode fiber. Adaptive optics is, from a quantum communication perspective, very interesting. In this paper, we present the overall system design, the optical and mechanical design, and the factory performance test results, of an adaptive optics module for post-compensation of the quantum signal in a QKD ground station. The set-up is integrated in a compact and transportable ""AO-box"". The AO-box has been designed to be directly mounted on the flange of an 80 cm fork mount telescope and delivers the fiber-coupled quantum signal at its output interface.