Fig. 1. Electromagnetic properties of ITO. (a) ITO electrical doping model; (b) change of carrier concentration with voltage; (c) change of dielectric constant with voltage; (d) change of accumulation layer thickness with original carrier concentration

Fig. 2. Structure of proposed phase modulating metasurface modulator. (a) Three-dimensional diagram; (b) unit cell (period P＝400 nm, metal connection line width W＝180 nm, metal disc diameter D＝280 nm, metal layer thickness T₁＝30 nm, insulating dielectric layer Al₂O₃ thickness T₂＝5 nm, and ITO film thickness T₃＝20 nm)

Fig. 3. Modulation performance and electric field distribution. (a) 310° phase tunability; (b) 320° phase tunability; (c) 330° phase tunability; (d) electric field distribution

Fig. 4. Reflection amplitude and phase as a function of bias voltage at different wavelengths. (a) Reflection amplitude; (b) reflection phase

Fig. 5. Influences of geometric parameters of proposed structure on phase modulation property. (a) Influence of width of metal strip W; (b) influence of thickness of top metal layer T₁

Fig. 6. Optical phased array design. (a) Schematic of phased array; (b) electric field distribution of beam deflection of 20°；(c) electric field distribution of beam deflection of 30°

Fig. 7. Directivity coefficient. (a) Beam deflection of 20°；(b) beam deflection of 30°

Fig. 8. Focus diagrams and phase distributions with focal lengths of 10, 15, and 20 μm. (a)(d) F＝10 μm; (b)(e) F＝15 μm; (c)(f) F＝20 μm

Fig. 9. Normalized focus electric field intensity in reflection direction (z-axis). (a) F＝10 μm; (b) F＝15 μm; (c) F＝20 μm

Fig. 10. Focusing effects after increasing the number of array elements to double or setting the uniform reflection amplitude. (a) F＝10 μm; (b) F＝15 μm; (c) F＝20 μm