Optical Interfaces in Reconfigurable Devices

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As users demand more multimedia, interactive, on demand and better quality services, the need to have wider bandwidths becomes more apparent. To overcome this fact, the optical communications are considered a good choice to fill these needs

Since many years ago the use of copper cables for data transmission is limited to local networks or to provide the last miles access to homes or offices. For longer distances and wider bandwidths, the optical fibre offers better transmission properties and a lower relative cost compared to copper cables. However, the starting cost and complexity for an optical system has been traditionally higher, due to the use of lasers, photodetectors and optical fibres that require a high mechanical precision for their deployment. During the last years, new technologies emerged allowing the arrival of the fibre to the home front door (FTTH) and even into the home using cheaper plastic fibre (POF) and LED light sources.

On the other hand, the electronic devices known as field programmable gate arrays (FPGAs) have increased their features, reducing their relative cost and electric consumption, becoming practical elements to be included in final products and not only for tests or laboratory prototypes. Some of those devices integrate specialized function blocks, such as memories, processors and communication interfaces, so it is possible to include almost every element of an electronic system into a single chip (SoC). Some important elements for high speed communications in FPGAs are the serializers and deserializers, which adapt the high speed data transmission (up to tens of gigabits per second) to the much lower internal working speeds of FPGAs, by means of serial/parallel conversions.

Until now, in order to use FPGAs with optical fibre it was necessary to use external modules to adapt the optical signals to electrical signals usable by the serializers and deserializers in the FPGAs. This solution involves the disadvantages of the high cost associated to those modules, their power consumption and the occupied space into the final products. The integration of those optical interfaces, which is currently under development by the industry, will imply a significant reduction in cost, consumption and space, enabling the addition of optical connectivity to consumer devices where they were unfeasible until now.

Gradiant carries out a permanent follow-up on these advanced communication technologies, keeping a fluent contact with the main manufacturers, in order to evaluate and incorporate them in its various research projects.