Dynamic beam all-direlectric coding metasurface converter based on phase change materials of GST

•We proposed the high-performance dynamic beam all-direlectric coding metasurface converter based on phase change materials of GST in optical communication band.•We found the theoretical support for optimizing geometric parameters by multipole decomposition and field diagram characterization of amorphous and crystalline elements. The optimized units can achieve ultra-high transmittance and 2π phase coverage in amorphous state.•The large contrast in transmittance and phase between the two states enables us to switch the beam deflection without changing the structure. And further applied it to the design of beam focusing and holographic reconstruction.•We arrayed the units into coding metasurface, and with the help of Fourier method, we realized the beam deflection at any angle in the working band of 1.119um. Phase change materials, especially Ge2Sb2Te5(GST), play an important role in the design of dynamic all-dielectric metasurface due to its flexibility and adjustability. And its non-volatility makes it possible to form dynamic metasurfaces with complex functions. In this paper, we propose a cross-shaped all-dielectric metasurface based on GST interlayer, which can achieve ultra-high transmittance and complete 2π phase coverage in the near-infrared band when the interlayer material is in amorphous state. Through multipole decomposition and field distribution characterization, we have revealed the regulation principles of the unit cell before and after the switching. And thus, we designed the arrays of metasurface with switchable beam deflection, arbitrary coding and focusing functions. Holographic reconstruction based on GS algorithm is discussed and extended to independent control of the RGB channels in imaging applications. Our research can provide a reference for the design of compact multifunctional optical elements, optical encryption and dynamic metasurfaces.