Ultrafast THz modulation characteristics of photo-induced metal-insulator transition of W-doped VO2 film

The ultrafast terahertz modulation characteristic during photoinduced metal-insulator transition (MIT) of W-doped VO2 film was investigated at picoseconds time scale using time-resolved terahertz spectroscopy. The phase transition dynamic process was dramatically suppressed in W-doped VO2 film, which could be ascribed to the lattice distortion and enhanced electron-electron interaction caused by W substitution for V. The transient complex terahertz conductivity of W-doped VO2 film at different pump-probe delay times were extracted and can be well fitted by Drude-Smith model, which provide significant insights into the dynamic properties of MIT in nanogranular VO2 film.