Metasurfaces have attracted immense interest across various scientific disciplines due to their ability to manipulate light wave parameters with numerous functionalities. However, these functionalities have historically been static, lacking the capability for dynamic, real-time control. In this study, we introduce a highly efficient, tunable waveplate by incorporating a thin layer of the phase change material Sb2Se3 into a silicon all-dielectric metasurface. This structure demonstrates the ability to transition from a half-waveplate to a quarter-waveplate as Sb2Se3 shifts from an amorphous to a crystalline state at the telecom wavelength of 1.55 μm. Remarkably, it maintains consistent performance across a range of rotation angles. In addition, we have performed comprehensive electro-thermal simulations to validate the phase change process, confirming the practical feasibility of this technology. This tunable metasurface represents a significant advancement in adaptive photonics, offering customizable and sophisticated functionalities.
In this paper, a transmissive tunable metasurface based on phase-change alloy Ge2Sb2Te5 (GST) has been proposed, exhibiting the function of switching between a quarter wave plate (QWP) and a half wave plate (HWP) in mid-IR region, i.e., providing circular-to-linear and circular-to-circular polarization conversions at amorphous state and crystalline state, respectively. For the amorphous GST, linear polarized (LP) transmitted beams with angles of linear polarization (AoLPs) close to ±45° can be obtained with the degrees of linear polarization (DoLPs) close to 1 under normal circular polarized (CP) excitations at the wavelength varying from 4.8 to 5.2 μm. As for the crystalline GST, the normally incident CP lights can be converted into the corresponding orthogonal CP beams with the degrees of circular polarization (DoCPs) close to ±1 within the wavelength range from 4.95 to 5.05 μm. The polarization state diagrams of the transmitted beams with good profiles further prove the good performance of the designed GST metasurface. Our finding paves the way for the development of flat polarization optical components with switchable functionalities.
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