Maybe this is the article?
Off-topic but nevertheless interesting.
http://www.spacedaily.com/news/supercomputer-01c.html
Currently all-optic logic gates are being developed but have to use lengths of optical fibre to delay some of the input beams. If silicon can be made to emit light then this brute force construction technique can be eliminated and all-optical computers will perhaps become affordable. Processing speeds are currently around 40 Gigahertz with up to 60 GHz expected for introductory personal computers based on optical processors. Quite a bit faster than Pentium 4 !