Fig. 1. Monoclinic and rutile crystal structures of vanadium dioxide^［109］

Fig. 2. Band structure of vanadium dioxide in metallic and insulating states^［113］

Fig. 3. The phase diagram of a vanadium dioxide thin film and the resistance-temperature curve^［125］

Fig. 4. Determined emissivity evolution of a vanadium dioxide thin film for increasing temperature^［126］

Fig. 5. Typical structures effectively improve the performance of smart window based on vanadium dioxide^［96］

Fig. 6. Phase transition of vanadium dioxide based on electrical excitation^{［71，136，138，143］}

Fig. 7. Transitional structures in phase transformations of vanadium dioxide by electron diffraction^［146］

Fig. 8. Dynamically tunable optical materials and devices based on phase transition of vanadium dioxide

Fig. 9. Tunable optical materials and devices realized by vanadium dioxide combined with plasmonic structures^{［62，67，83，157］}

Fig. 10. Tunable optical materials and devices realized by vanadium dioxide combined with metamaterials^{［85，99，167，175］}

Fig. 11. Tunable optical materials and devices realized by vanadium dioxide combined with metasurfaces^{［66，69，187］}

Fig. 12. Tunable optical materials and devices realized by vanadium dioxide combined with waveguides or gratings^{［105-106，198］}