Refractive-index-adjustment of SiO –GeO films deposited by 2 2 radio frequency magnetron sputtering

Oxygen annealing of the SiO2–GeO2 films has been investigated to control the value of the refractive index. The fluctuation of the refractive index of as-deposited films became the order of less than 10y4 by annealing in the O2 atmosphere for 3 h at temperatures of 9008C or higher. Using this oxygen annealing, the refractive index could be controlled over a wide range of values from 1.4467 to 1.4740 at 1550 nm by selecting the deposition condition of rf-power and two GeO2 targets with different concentration. The optical attenuation was very low: less than 0.1 dBrcm at 1550 nm. q1999 Elsevier Science B.V. All rights reserved