Numerical Modeling of Tunable Reflection Scattering Angle Control Based on Ge2Sb2Te5 Phase Change Metamaterials

To reduce the ohmic loss of the encoding metasurface and achieve continuous control of the scattering angle larger than 70°, we numerically study all dielectric reflective metasurface in the mid-infrared waveband. Free control of the deflection angle of the far-field scattered beam is achieved. The unit structure designed consists of the Ge₂Sb₂Te₅ phase change material and the substrate. The phase difference between each two-unit structures is 90° and has high reflectivity in the working band. We can arrange the four units to construct metasurfaces with different coding sequences and perform Fourier convolution operations on the metasurfaces with different coding sequences to obtain flexible control of the reflected beam. The reflection characteristics of the coding sequence in the crystalline and amorphous states of the Ge₂Sb₂Te₅ phase change material are demonstrated. The abnormal reflection angle phenomenon of the simulated structure was theoretically analyzed.