Fig. 1. Schematic illustration of the unit cell structure. The +σ denotes the right-handed circularly polarized light, and the −σ denotes the left-handed circularly polarized light.

Fig. 2. (a) Schematic illustration of the designed supercell structure that exhibits opposite phase gradient profiles for each phase of GST. Designed four unit cells are arranged in numerical order to the +x direction. (b) Numerically calculated phase shifts corresponding to each unit cell that are presented by step functions for two respective phases of GST.

Fig. 3. Variation trend of complex amplitude of transmitted LCP light according to w and d values for two distinct phases of GST. (a) The phase of complex amplitude and (c) its absolute value at the crystalline phase. (b) and (d) present those of the amorphous phase, respectively. The black rectangles, blue circles (in the middle of each figure), and red circles (in the leftmost of each figure) denote the selected dimensions of GST nanorods.

Fig. 4. (a) Desirable phasor map of transmitted LCP light of unit cell 2 for each phase of GST. (b) The schematic illustration of unit cell 2. (c) Phase and amplitude variation plot according to varying θl for two distinct states of GST. The vertical dotted line indicates the selected angle of θl=100°.

Fig. 5. (a) Angular radiation intensity pattern of transmitted LCP light for two distinct states of GST and (b) the corresponding LCP electric field profiles.