Fig. 1. (a) SEM image, (b) EDS pattern, (c) linear absorption spectrum, and (d) linear complex permittivity of the AZO film. The shaded part in (d) represents the ENZ region.

Fig. 2. (a) Transient absorption spectra of the AZO film with a 350 nm pump. (b) Extracted carrier time response parameters: fast decay time τ₁ (red hexagons) and slow relaxation time τ₂ (purple rhombuses) under various probe wavelengths. Temporal evolution of the optical density change (ΔmOD) at (c) 517 and (d) 600 nm probe wavelengths.

Fig. 3. (a) Open-aperture and (b) closed-aperture results of the AZO film at the ENZ wavelength under different incident intensities.

Fig. 4. Plot of ln(ΔT) as a function of ln(I).

Fig. 5. (a) β (red dots) and (b) n₂ (purple quadrates) under different excitation wavelengths.

Fig. 6. Experimental setup for THG measurement.

Fig. 7. (a) THG spectra under diverse incident wavelengths. (b) THG spectra under various excitation intensities at 1550 nm. (c) Dependence of THG power and excitation power. (d) Calculated THG efficiency at different excitation wavelengths.