Abstract
Abstract Plasmonic Fano resonance (FR) that contributes to multitudinous potential applications in subwavelength nanostructures can facilitate the realization of tunable wavelength selectivity for controlling light–matter interactions in metasurfaces. However, the plasmonic FR can be generated in metasurfaces with simple or complex geometries, and few of them can support flexible amplitude modulation and multiwavelength information transfer and processing. Here, we study the near-infrared plasmonic FR in a hybrid metasurface composed of concentrically hybridized parabolic-hole and circular-ring-aperture unit cells, which can induce polarization-dependent dual-wavelength passive plasmonic switching (PPS) and digital metasurface (DM). It is shown that the designable plasmonic FR can be realized by changing the geometric configurations of the unit cells. In particular, owing to the polarization-dependent characteristic of FR, it is possible to fulfill a compact dual-wavelength PPS with high ON/OFF ratios in the related optical communication bands. Moreover, such PPS that manipulates the amplitude response of the transmitted spectrum is an efficient way to reveal a 1-bit DM, which can also be rationally extended to a 2-bit DM or more. Our results suggest a pathway for studying polarization-dependent PPS and programmable metasurface devices, yielding possibilities for subwavelength nanostructures in optical communication and information processing.
Highlights
The Fano resonance (FR) is an interference phenomenon widely studied in the light–matter interaction systems, which is caused by the interference between a narrow discrete resonance and a broad spectral continuum [1,2,3]
We show that the plasmonic FR originates from the destructive interference between the superradiant and subradiant plasmonic modes with the spectral overlapping in the hybrid metasurface, which agrees well with the temporal coupled-mode theory (TCMT)
The bonding mode can be considered as the effective electric dipolar mode D1, the hybridized plasmonic wave functions contain an admixture of DPH and QPH modes [45]
Summary
The Fano resonance (FR) is an interference phenomenon widely studied in the light–matter interaction systems, which is caused by the interference between a narrow discrete resonance and a broad spectral continuum [1,2,3]. Therein, the dynamic metasurfaces with tunable characteristics including the optical phase and amplitude can be used to construct electromagnetic devices with reconfigurable or programmable functions, such as information processing [32] and digital metasurface [33, 34], and achieve advanced multifunctional systems [35,36,37]. We numerically study the near-infrared plasmonic FR in a hybrid metasurface that consists of parabolic-hole (PH) and circular-ring-aperture (CRA) unit cells for the realization of the polarization-dependent dualwavelength passive plasmonic switching and digital metasurface. By varying the polarization direction, a compact polarization-dependent dual-wavelength passive plasmonic switching can be implemented at the telecom O- and L-bands, respectively, with the ON/OFF ratio being 21.98 and 15.96 dB Such passive plasmonic switchings can be put forward for accomplishing a 1-bit digital metasurface, which can be extended to a 2-bit digital metasurface or more. Our results provide an alternative way for the multifunctional digital metasurface devices and can be extended to all-optical regions
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