Ruprecht-Karls-Universität Heidelberg


High Density Active Optical Cable

 Picture of the HD-AOC-Logo

Description

Active Optical Cables (AOC) combine the benefits of electrical connectors and optical transceivers. The concept allows high-speed interconnects with 12.5Gbps per channel for distances of up to several 100m. The ZITI research group High Speed Short Range Interconnects develops a prototype of a 12x AOC based on our patented fiber coupling and replication technology. By integrating the electrical-optical conversion into a mini-HT connector, the HD-AOC is going to be the densest connector system world wide.

Mini-HT connector

The new connector concept was developed in cooperation with the CAG and the US company Samtec. The connector is based on the idea to integrate 6 ports on a backplane of a standard PCI-E or HT extension cards in order to build a 3D-torus interconnection network. Each connector integrates 12 channels providing a maximum bandwidth of 150Gbps per interconnect or 900Gbps per board using 6 links.

                    Mini-HT cable system, 12x electrical or optical version

Electric-optical conversion

VCSEL (Vertical Cavity Surface Emitting Lasers) are replacing edge emitting lasers in high speed optical interconnects due to their better beam characteristics and fabrication advantages. They emit the optical signal perpendicular to the reference plane, e.g. the board. Since the fiber attachment is in plane with the board, the light from the VCSEL has to be redirected by 90° inside the very small volume of the connector. Therefore, we developed and patented in cooperation with the Chair of Optoelectronics a new concept of fiber coupling. It is based on an integrated fiber coupler combing four functions into one replicable structure: 90° light deflection, fiber guiding, fiber funnels, and focusing.

                   12x VCSEL to fiber coupler

Development of a 12x HD-AOC prototype

An AOC, in general, consists of 4 parts: the connector housing, the interposer RX and TX, the fiber coupling structures, and the fiber attachment. In cooperation with the Chair of Optoelectronics, the CAG developed an interposer with integrated fiber coupling structures for the electrical-optical conversion inside the mini-HT connector. The assembly of the electrical interposer parts is realized at the Karlsruhe Institute of Technology while the CAG integrates the fiber coupling structure, attaches the fibers, and develops the test environment.

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