Fig. 5

Expected functionality, sample picture, and experimental characterization of the bi-channel meta-device II. a The proposed meta-device II is expected to covert the incident LCP light to a focused vortex SPP in the NF channel and reflect the incident RCP light to a spatial vortex beam in the FF channel, with vertices’ topological charges being 7 and -9, respectively. b SEM image of the fabricated sample, with its zoomed-in images shown in the inset. As the meta-device is shined by LCP light at 1064 nm, c the LRM-recorded field pattern of the vortex SPP generated on the metallic surface and d the CCD-captured field pattern as the vortex SPP interferes with a spherical wave. As the meta-device is shined by RCP light at 1064 nm, e the CCD-captured field pattern of the vortex beam reflected by the device and f the CCD-captured field pattern as the vortex beam interferes with a spherical wave