Superconducting Technology Assessment - nitrd

DATA SIGNAL TRANSMISSION
ABSTRACT
This chapter evaluates the candidate technologies for data signal transmission from the core processors, operating
at cryogenic temperatures, to the large (petabytes) shared data memory at room temperature and at some distance
(tens of meters). The conclusion reached is that the only technology capable of providing the very large bandwidth
requirements of the computer architecture required to meet government needs, the distances this data must be
moved, and the operation of the superconductive processor at 4K, is massively parallel optical interconnects.
Because of the limitations of current opto-electronic devices, a specific system configuration appears optimal: placing
the 4K to 300K transmission components at an intermediate temperature within the cryogenic housing.
A number of alternative approaches are suggested whose goals are to:
■ meet the exacting bandwidth requirements.
■ reduce the power consumption of cryogenically located components.
■ reduce size and cost by advances in component integration and packaging beyond
the foreseeable needs of the marketplace in the 2010 time frame.
A listing of the specific efforts, their current status, and goals is shown, along with a roadmap to achieve the data
signal transmission capabilities required to start the construction of a superconductive supercomputer by 2010.
Contents:
1. Current Status of Optical Interconnects
1.1. Comparison of Optical and Electrical Interconnects for Superconductive Computers
1.2. Current Optical Interconnect R&D Efforts
2. Readiness for major investment
3. Issues and concerns
3.1. Data Rate requirements
3.2. Issues of Using Optics at 4K
3.3. The 4K-Intermediate Temperature Electrical Option
3.4. Coarse vs. Dense Wave Division Multiplexing (CWDM vs. DWDM)
3.5. Developments for Low Temperature Opto-electronic Components
4. Conclusions
5. Roadmap
6. Funding
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