Channel waveguides formed by ion implantation of PECVD grown silica

Low loss channel waveguides have been formed in silica-on-silicon by implantation with 5 MeV Si and Ge ions. In these experiments, the substrate was comprised of an undoped layer of silica (30 μm thick) which was grown by plasma enhanced chemical vapour deposition (PECVD). The optical loss characteristics of the waveguides, as measured at both λ=1300 and 1550 nm, were independent of the implanted ion species, A minimum in the attenuation loss (α) of ~0.10-0.20 dB/cm was obtained following both a pre-implant (1050°C) and a post-implant (400-500°C) anneal of the waveguides. The ability to produce a minimum in a by pre-implant annealing has been attributed to the thermally induced relaxation of the densified structure in the as-grown layer. Only a comparatively small degree of compaction was measured for Si-implanted samples which did not receive a pre-implant anneal. In contrast, the much larger degree of compaction in the pre-implant annealed samples was similar in magnitude to that observed in fused silica. These are the first reported examples of ion-implanted waveguides using a substrate of silica grown by PECVD