Fig. 1. Refractive index curves of H4 films at different substrate temperatures

Fig. 2. Atomic force microscope (AFM) images of surface morphology of H4 films at different substrate temperatures. (a) 125 ℃; (b) 150 ℃; (c) 175 ℃; (d) 200 ℃

Fig. 3. Refractive index curves of H4 films at different ion-beam densities

Fig. 4. AFM images of surface morphology of H4 films at different ion-beam densities. (a) 105 μA·cm^-2; (b) 120 μA·cm^-2; (c) 135 μA·cm^-2; (d) 150 μA·cm^-2

Fig. 5. Extinction coefficient of H4 films at substrate temperature of 175 ℃ and ion-beam density of 120 μA·cm^-2

Fig. 6. Transmittance spectra of H4 films after post-treatment. (a) High temperature annealing; (b) plasma post-treatment

Fig. 7. Reflectance curves of HR films of different materials. Solid line is theoretical value and dotted line is measured value

Fig. 8. Damage morphology of HR films under laser power density of 600 MW/cm². (a) HR films of TiO₂; (b) HR films of Ta₂O₅; (c) HR films of H4