Fig. 1. Optical alignment of OPTP system

Fig. 2. Characterization of 30 nm 1T′-MoTe₂ thin film on quartz substrate. (a) Room-temperature Raman spectrum of 1T′-MoTe₂; (b) room-temperature XRD pattern of 1T′-MoTe₂, and the peak of SiO₂ is indicated by the arrow; (c) terahertz transmission spectra in time-domain without the sample (dashed line) and with the sample (solid line); (d) terahertz transmission spectra in frequency-domain without the sample (dashed line) and with the sample (solid line)

Fig. 3. Transient terahertz transmittance of 30 nm 1T′-MoTe₂ on quartz substrate at room temperature under the photoexcitation of 780 nm as well as the fitting results. (a) Transient terahertz transmittance with various pump fluences, and the inset shows the normalized result of dashed box; (b) transient terahertz transmittance of long time scale scanning under pump fluence of 356.51 μJ/cm², and the inset shows the biexponential fitting results; (c) pump fluence dependent terahertz peaking transmittance; (d) pump fluence dependence of fast process lifetime τ₁ obtained from biexponential fittings, the solid line shows the fitting curve with two-temperature model

Fig. 4. Complex photoconductivity of 1T′-MoTe₂ film under the excitation of 780 nm laser along with the Drude‒Smith fitting results under different delay time. (a) Transient terahertz complex photoconductivity at different delay time; (b) ωp with respect to delay time; (c) τ with respect to delay time; (d) c with respect to delay time

Fig. 5. Dispersion of complex photoconductivity of 1T′-MoTe₂ at different delay time and the fitting results with Drude‒Smith model. (a) Transient terahertz complex photoconductivity under different pump powers; (b) ωp with respect to pump power; (c) τ with respect to pump power; (d) c with respect to pump power