This invention relates to optical interconnects for chip-to-chip communication. In particular it relates to the use of materials that propagate light faster than the speed of light in optical fibers or even faster than free-space light transmission.
As described by Li in U.S. Pat. No. 6,661,943, state of the art microelectronic systems commonly employ multichip modules. A multichip module includes an array of integrated circuit chips that require signal interconnections between the chips. Next-generation computational systems require ever increasing speeds. Using shorter interconnect path lengths and increasing the speed of information over that path are ways to enhance speed.
An optical interconnect that passes information between chips faster than electrical or optical fibers or waveguides has been invented. This interconnect uses silver or some other metal or Nitride to transmit the light between chips. It has been discovered that light travels faster than c, which is the speed of light in a vacuum, when traveling through silver, gold, copper, and some other metals.
As described in the book Thin-Film Optical Filters by H. Angus Macleod, third edition, Taylor & Francis, New York (2001) Ch. 2, light energy is transferred as a wave with a velocity v according to the refractive index n of the optical material following the relation v=c/n. It turns out that n for silver is less than unity. This would mean that light travels faster than c in silver. However, silver is a metal that also absorbs light, so it is not clear in the literature that the speed of light in silver would be faster than c. In fact there is a strongly held belief that light and especially information cannot travel faster than c. I have discovered theoretically that although the light is being attenuated, it does not slow down when propagating through small distances in silver and actually speeds up to many times faster than in air. With the ever decreasing distances on chips it has or will become feasible to use silver as an optical interconnect. Light in silver travels eight times faster than in air or vacuum.
Provisional application No. 61/396,894 filed on Jun. 04, 2010.
This invention was made with Government support under contract F36615-03-D-5408 awarded by U.S. Air Force to General Dynamics Information Technology, Inc. who subcontracted to Table Mountain Optics under Task Order No. USAF-5408-23-SC-0010-1 Modification #001. The Government has certain rights in the invention.
Number | Date | Country | |
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61396894 | Jun 2010 | US |