Method for parallel fabrication of large area waveguide structures
Original Publication Date: 2002-Nov-11
Included in the Prior Art Database: 2003-Jun-21
*Main Idea Transmission of very fast signals (10Gbit/s and more) over large distances (1 m) is becoming increasingly difficult for conventional copper based technologies. The use of optical signal transmission is generally considered as a promising solution to this problem. There has been a wealth of approaches for optical interconnects, depending on the speed, length and type of application. This invention addresses the approach of using waveguides that are integrated directly with a large backplane-type printed circuit board. Such boards can be up to 130 cm x 65 cm large. To practically integrate waveguide structures into or onto such large boards, there have been again several approaches, but all of these approaches are prototype/feasibility demonstrations or solutions for a restricted (low-volume) application space. As far as known, none of the current waveguide fabrication methods is able to provide a mass-producible way of defining large structures with high-quality waveguides. In general, there is a trade-off between overall size and resolution for technologies such as etching and lithography. While the currently known approaches fail to satisfy all requirements simultaneously, this will be a "conditio sine qua non" for waveguide based intra-shelf interconnects. The need for optical interconnects within high-end systems mainly comes from length limitations of current copper technology. Optics will therefore be needed for larger in-box distances first (i.e. 1m card-to-card over a backplane and not 30 cm on-board). To provide the tens of Terabit/second aggregate throughput that future high-end systems will need, individual line speed and density will also have to be pushed to their limits. For the waveguide technology, this will result in a need for small waveguide structures (50 micrometer and smaller) in order to provide the high density and to avoid modal dispersion problems of large 100 um) waveguide cores at very high channel-speed. As mentioned above, none of the currently known approaches provides large sample size, fine-resolution and mass-producibility simultaneously.