Polarization-multiplexed metaholograms with erasable functionality

Abstract

The unprecedented capability of metasurface in pixel-wise-level accurate light manipulation has enabled the realization of polarization-multiplexed metasurface holograms in a single or multiple channel. However, most metasurfaces are static and unable to realize active or tunable wave control in many scenarios. We introduce erasable functionality to the multi-channel metasurface holograms based on the active phase tuning, which is realized using the nonvolatile chalcogenide phase change alloy of GeSbSeTe (GSST). Upon the incidence of linearly or circularly polarized waves, the polarization-dependent holograms constructed by amorphous GSST elliptical pillars are achieved due to the complete phase control. The a-GSST holograms feature a subwavelength spatial resolution and an estimated efficiency ranging from 66% to 90%. Benefiting from the amorphous-to-crystalline phase transition of GSST, the hologram functionality can be totally erased since the crystallized pillars cannot provide effective propagation modes required by the anisotropic phase modulations in the operating wavelength range. The unique property of the proposed polarization-multiplexed holograms with erasable functionality offers more degrees of freedom and has potential applications in many fields such as anti-counterfeiting, encryption, and holographic sources..

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