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Optoelectronics comes of age, part 2: optical connectivity is sufficiently advanced, has been reduced to practice and is available for many near term applications.

Article Excerpt
Over the last 20 years there have been many process and material technologies used to develop planar polymer waveguides containing films capable of meeting the current and evolving industry requirements. Sorting through the various techniques used to make polymer waveguides, these processes fall into two basic classes, both using photolithographic processes (sometimes with LDI) to define the waveguide. The distinctly different processes for the two classes are:

Ridge technology. Initially, a polymer ridge or trench is constructed through molding, embossing, or etching that has a higher refractive index than the base polymer. See FIGURE 1 for a schematic outlining the generic process steps for ridge and trench polymer waveguide formation. The lower refractive index polymer surrounding the waveguide region creates the specific guiding properties. Different polymer materials have been evaluated depending on whether a ridge or trench is used to form these waveguides.

[FIGURE 1 OMITTED]

Diffusion Technology. This method includes the formation of a high refractive index waveguide by monomer diffusion into the light-exposed guide forming region with no mechanical or chemical etching contact. See FIGURE 2 for a schematic showing the diffusion technique process. An essential process feature here is the photomask-defined light exposure of a mobile monomer waveguide forming region in a polymer matrix that converts the monomer to a polymer. The process of continued monomer diffusion into the surrounding guide imaged region increases the density. The addition of other laminated monomer/polymer diffusing layers with the typical three-plus layer configuration is completely photopolymerized after diffusion is complete. The essential steps include a light induced imaging reaction, a total polymerization light fixing for the entire film, and final cure, all using pre-coated dry materials without waveguide side wall contact. Light and molecular diffusion determine the guide...