Relative-cavity-length-controlled slow light in a cascaded magnon-photon system

We theoretically discuss the input-output characteristics of the cascaded magnon-photon system by focusing on the slow light effect caused by positive group delay. When two identical magnon-photon systems are cascaded, compared with the single cavity system, the bandwidth of the whole system is wider, but the group delay is smaller. The change of the group delay is different from that of the general linear system. Moreover, by changing the cavity length of the two microwave cavities, the system is slightly mismatched and the group delay could obviously increase. The slow light effect could be controlled by relative cavity length. The slow light effect of the mismatched double cavity system is more sensitive to external magnetic field than that of the single cavity system. The results provide a way to manipulate the transmission rate in optical information networks and a new view about the interconnection of microwave cavities.