[[abstract]]Ion-beam-sputtered TiO2–SiO2 mixed films with 17% SiO2 concentration were used as high-refractive-index layers in a multilayered-stack dielectric mirror. Experimental results indicated that total loss of the as-deposited mirror was 34% lower than that of the as-deposited conventional mirrors with pure TiO2 films used as high-refractive-index layers. In addition, annealing reduced total loss of the mirrors. Although decreasing with an increasing annealing temperature, total loss of the conventional mirrors dramatically increased above ~200 °C annealing temperature, owing to increased scattering from an amorphous-to-crystalline phase transition in the TiO2 films. In addition, total loss of the mirrors with the mixed films continuously decreased with an increasing annealing temperature up to 400 °C without the phase transition. Total loss was reduced 88% by means of decreasing absorption in the mixed films. Moreover, the annealed mirror with mixed films was better than both the as-deposited mirror and the conventional mirror with pure films in terms of laser-damage resistance.
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