Formation of optical barriers with excellent thermal stability in single-crystal sapphire by hydrogen ion implantation and thermal annealing

We report a study on the use of hydrogen ion implantation to form optical barriers with excellent thermal stability in single-crystal sapphire. Sapphire crystals are implanted with H ions of energies 0.2–1 MeV to doses 1016–1017 cm−2, followed by thermal annealing between 600–1200 °C. Prism coupling experiments and spectroscopic ellipsometry indicate the formation of an optical barrier with decreased refractive index around the projected range of H ions in sapphire. The refractive index reduction is found to increase with annealing temperatures, reaching a maximum of ∼3.2% following annealing at 1200 °C. The correlation of the structural properties with the formation of optical barriers and their thermal stability in sapphire crystals, is duscussed.

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