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Geometric phase metasurfaces, as one of the main branches of meta‐optics, have attracted enormous interest in the last two decades. Recently, through rotating a set of subwavelength dipole sources, geometric phase concept has been extended to near‐field regime for the control of surface plasmons (SPs). Despite this progress, puzzles and shortcomings still exist: it is curious that geometric phases equal to once and twice the rotation angle of dipole source are both reported for SP controls, and the control strategies examined thus far only work for a single wavelength. Hereby, a rigorous derivation of the SP excitation of dipole sources upon circularly polarized illumination is performed, and the rotation dependence and in‐plane coordinate correlation of geometric phase control of SPs is clarified. Moreover, a holographic approach is proposed to implement multiplexed geometric phase control, experimentally demonstrating several metalenses that can couple and steer the incident circular polarizations of four wavelengths and two spin directions to different SP focusing beams. This work will pave an avenue toward the development of integrated and multiplexed SP devices. [ABSTRACT FROM AUTHOR]

Spoof surface plasmon polaritons (SPPs) with strong subwavelength field confinement and enhancement offer a promising way for realizing integrated on‐chip terahertz (THz) devices. How to find a simple way to control the dispersion of spoof SPPs and then achieve functional on‐chip devices is thus highly desired. Here, the authors theoretically and experimentally demonstrate that such a method can provide sufficient design degrees of freedom to enable versatile THz spoof SPP metadevices. As a proof‐of‐concept demonstration, a series of on‐chip meta‐devices including the switch, the wavelength demultiplexer, and the splitters are presented. The proposed strategy paves a simple way toward the integrated on‐chip THz devices with various functionalities. [ABSTRACT FROM AUTHOR]

Abstract: Surface plasmons (SPs) promise versatile potential applications in many aspects and thus have been a subject of enormous interest. As the most essential functionality, efficient coupling of free‐space light into complex SP field is of particular interest in current research. Most existing methods only focus on either efficient coupling or complex SP field generation, which is insufficient to support the ever‐increasing demand of practical applications. Herein, it is demonstrated both theoretically and experimentally that a metasurface composed of properly designed C‐shaped slit resonators can function as an efficient SP coupler. More importantly, it is shown that the phase and amplitude of the coupled SPs can be simultaneously manipulated, which would offer considerable design flexibilities for complex SP launching. This methodology can provide a wide platform for the design and fabrication of high‐performance plasmonic devices in the future, especially large‐area ones in practical applications. [ABSTRACT FROM AUTHOR]

The ability of generating arbitrary surface plasmon (SP) profiles in a controllable manner is of particular interest in designing plasmonic imaging, lithography and forcing devices. During the past decades, holography has gained enormous interest and achievements in free-space three-dimensional displays. Here, by applying a two-dimensional version of holography, we experimentally demonstrate a generic method to control the SP profiles. Through controlling the orientation angles of two separated slits under circular polarization incidence, the amplitude and phase of the excited SPs can be freely manipulated, which allows direct generation of the desired SP profiles. A series of controllable SP holography schemes are theoretically and experimentally demonstrated, where the holographic SP profiles with high imaging quality can be dynamically modulated by varying the circular polarization handedness or orientation angle of linear polarization. The universality and simplicity of the proposed design strategies would offer promising opportunities for practical plasmonic applications. [ABSTRACT FROM AUTHOR]

Orbital angular momentum (OAM) has been recently introduced to plasmonics for generating plasmonic vortices with a helical wavefront, opening avenues for exotic on‐chip applications such as quantum information processing and communications. In previous demonstrations, carefully designed optical elements are used to convert left‐ and right‐circular polarizations into plasmonic vortices with different topological charges, resulting in conversion from optical spin angular momentum (SAM) to plasmonic OAM. Here, it is demonstrated theoretically and experimentally that by utilizing the near‐field coupling between paired resonators in a metasurface, selective conversion from optical SAM to plasmonic OAM is realized, where generation of plasmonic vortices can be achieved for incident light of one circular polarization while significantly suppressed for the other circular polarization. The proposed design scheme may motivate the design and fabrication of future practical plasmonic devices. [ABSTRACT FROM AUTHOR]