| 摘要 |
The invention resides in a method of forming a waveguide structure comprising the steps of forming a silica based waveguide on a substrate; annealing one or more localised regions of said waveguide to permanently set the refractive index profile of said localised regions relative to other regions of said waveguide. In a particular form of the invention a core-forming layer is formed and selected regions of the core-forming layer are annealed to reduce their refractive, index thereby defining a core region therebetween. Other applications of the invention reside in reducing bend losses in bent waveguides, and forming long-period gratings in planar waveguides.
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