Retroreflectors
that can accurately redirect the incident waves
in free space back along their original channels provide unprecedented
opportunities for light manipulation. However, to the best of our
knowledge, they suffer from either the bulky size, narrow angular
bandwidths, or time-consuming postprocessing, which essentially limits
their further applications. Here, a scheme for designing ultrathin
all-angle real-time retroreflectors based on hyperbolic plasmonic
metasurfaces is proposed and experimentally demonstrated. The physical
mechanism underlying the scheme is the orthogonality between the traveling
waves in free space and the canalized spoof surface plasmon on the
hyperbolic plasmonic metasurfaces, which guarantee their high-efficiency
and all-angle mutual conversion. In this case, the strong confinement
characteristic that benefited from the enhanced light–matter
interaction enables us to route and retroreflect the canalized spoof
surface plasmon with extremely thin structures. As proof of the scheme,
a retroreflector prototype with a thickness approximately equal to
the central wavelength is designed and fabricated. Further experimental
investigation obtains a half-power field of view up to 53° and
a maximum efficiency of 83.2%. This scheme can find promising applications
in target detection, remote sensing, and diverse on-chip light control
devices.
Surface waves (SWs) are of great importance in terahertz (THz) photonics applications, due to their subwavelength properties. Hence, it is crucial to develop surface wavefronts shaping techniques, which is urgent...
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