摘要 |
<p>A QKD cascaded network (5) with loop-back capability is disclosed. The QKD system network includes a plurality of cascaded QKD relays (10, 20, 30) each having two QKD stations Alice (A) and Bob (B) therein. Each QKD relay also includes an optical switch (50). The optical switch is optically coupled to each QKD station in the relay, as well as to the input ports (PI) of the relay. In a first position, the optical switch allows for communication between adjacent relays. In a second position, the optical switch allows for pass-through communication between the QKD relays (10 and 30) that are adjacent the relay whose switch is in the first position. Also in the second position, the optical switch allows for communication between the QKD stations A and B within the relay. This, in turn, allows for diagnostic measurements to be made of one or both of the QKD stations via an optical path (90) that is entirely within the relay station enclosure (12, 22, 32).</p> |