Superconducting Technology Assessment - nitrd

A development in long haul communications technology which is rapidly approaching implementation into 40
Gbps systems is the use of differential phase shift keying (DPSK) in place of the conventional on-off keying normally
used (and used in the above described systems). While the receivers are slightly more complex, this allows the use
of simpler transmitters, which is of great advantage in this application (see Sections 3.2 and 3.3)
There are also a number of very interesting developments in exotic materials and devices which have the potential
to greatly reduce the cost of these components and systems well beyond the scope of the efforts mentioned above.
One area, funded under the DARPA MORPH program, includes the development of organic glasses and polymers
which may be capable of producing optical modulators with very low modulation powers, as well as allowing
simple fabrication techniques for large arrays. Another area, once funded by ONR, is the use of magneto-optic
modulators directly driven by the superconductive circuitry. This would be the optimal solution since it would
eliminate the need for any amplifiers and would operate at 4K. While in an earlier stage of development than the
abovementioned efforts, one of these may become available in time for the construction of a full scale petaflop
supercomputer starting in 2012, while a demonstration system could be built using the less advantageous
technology available in 2010.
2. READINESS FOR MAJOR INVESTMENT
There is considerable interest in some parts of the computer industry to move into optical interconnects, as is
evidenced by the IBM and Agilent co-funding of their above described efforts sponsored by DARPA under the
Terabus program, which are described above. DARPA funding has been about $7.5M over an 18 month period. It
can be expected that the companies and universities who are already involved in this effort could absorb a major
increase to speed up the effort without straining their resources. In fact there are a number of other companies
who have already expressed interest in this area.
Though Intel interests are broader than only short range (100 Gbps, the widespread use of
such rates is not likely in the next 5-10 years; therefore production technology to meet the 2010-2014 target dates
for a superconductive supercomputer will not be available.
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