HIGH-TEMPERATURE ANNEALING OF HE+ ION-IMPLANTED QUARTZ OPTICAL WAVE-GUIDES

The refractive index changes produced by high energy He+ ion implantation in crystalline quartz exhibit almost idealised behaviour for optical waveguide formation. There is a high efficiency for nuclear damage which amorphises the lattice at a low dose (< 1016 cm-2), producing a reduced refractive index optical barrier with - Δn ∼ 5%. The electronic stopping has very little effect on the index, and absorption due to colour centres is removed by annealing at ∼ 600°C. By means of multi-energy implants it is therefore not difficult to produce low loss guides (∼ 0.2 dB/cm) having a wide variety of profile specifications, and very easy to produce guides with almost square-barrier profiles. We report the annealing characteristics of these profiles at temperatures up to 1000 ° C where the high damage region of the barrier (- Δn > 2%) increases (towards the fused silica value) and the low damage region decreases towards that of crystalline quartz. The annealing behaviour is compared with that of ion-damaged fused silica. © 1990.