We propose a scheme to realize the storage and retrieval of high-dimensional electromagnetic waves with orbital angular momentum (OAM) via plasmon-induced transparency (PIT) in a metamaterial, which consists of an array of meta-atoms constructed by a metallic structure loaded with two varactors. We show that due to PIT effect the system allows the existence of shape-preserving dark-mode plasmonic polaritons, which are mixture of electromagnetic-wave modes and dark oscillatory modes of the meta-atoms and may carry various OAMs. We demonstrate that the slowdown, storage and retrieval of multi-mode electromagnetic waves with OAMs can be achieved through the active manipulation of a control field. Our work raises the possibility for realizing PIT-based spatial multi-mode memory of electromagnetic waves and is promising for practical application of information processing with large capacity by using room-temperature metamaterials.
Fig. Storage and retrieval of the signal pulse. Evolutions of the signal field |Emp|/E0 (a) and the dark-mode oscillation |˜qmp− |/q0 (b) as functions of z and t/τ0 for γt = 10 −3ωr. (c) and (d) show, respectively, the evolutions of |Emp|/E0 and |˜qmp − |/q0 as functions of z and t/τ0 for γt = 10 −4ωr. The red solid, green dashed, and blue dashed-dotted lines are for z = 1 cm, 8 cm, and 15 cm, respectively. The control field Ωcτ0 is switched off at t = Toff = 0 and switched on at t = Ton = 25τ0 with τ0 = 10ns, shown by blue solid line in each panel.
