ALBUQUERQUE, N.M. — In their greatest success, researchers Shawn Lin and Jim Fleming at the US Department of Energy’s Sandia National Laboratories have created a microscopic three-dimensional lattice that confines light at optical wavelengths.
Fabricated from tiny slivers of silicon, the device when magnified resembles nothing so much as an edifice constructed from toy Lincoln Logs.
The proof-of-principle achievement, reported in the Jan. 1, 1999, Optics Letters, may prove commercially important to the fiber-optics communications industry because the technique appears to be the cheapest, most efficient way to bend light entering or emerging from optical cables, says Lin.
Says physics Nobel laureate (1998) and Princeton University professor Daniel Tsui, “Shawn’s work is very important. Its applications are imminent in the world of photonics. It means that bending light becomes easy.”
The optical lattice is ten times smaller than the infrared device the Sandia researchers recently reported in Nature.
“In my mind,” says Lin, “we are on holy ground. We are the lucky ones who got to the moon first.”
The device is called a photonic crystal because its regularly repeating internal structure can direct light, thus mimicking the properties of a true crystal but — since its internal dimensions can be created at optimum sizes — with far greater ability to select desirable wavelengths.
The device traps light within the structure’s confines as though reflecting it by mirrors, and makes possible transmission and bending of electromagnetic waves at optical frequencies with negligible losses.
The crystal is the smallest ever fabricated with a complete three-dimensional photonic band gap. It is effective at wavelengths between 1.35 and 1.95 microns. A micron is about 1/70 the diameter of a human hair.
The lattice’s creation crowns a quest in laboratories around the world that began 10 years ago with the simple idea that a light-containing artificial crystal was possible.
“The present structure is a monumental achievement,” says Sandia manager Del Owyoung. “It’s a fabrication that researchers have been trying to achieve for a decade.”
The field of research was suggested to Lin by Tsui in 1992 who said the idea possibly came out of a discussion the pair had about devices of the future. “Shawn is very creative,” says Tsui.
The structure — a kind of microscopic tunnel of silicon slivers with a 1.8-micron minimum feature size — was created at Sandia’s Microelectronics Development Laboratory.
A paper on larger-dimensioned fabrications at Sandia to control electromagnetic waves in the microwave range, achieved with proportional dimensions contributed by scientists at MIT, appeared last year in Science.
Still to be achieved in the optical range is the insertion of a defect that can transmit and bend light within the lattice structure.
Previous stories and visuals:
http://www.sandia.gov/media/linpaper.htm and https://newsreleases.sandia.gov/lincoln-log-like-structure-to-improve-infrared-and-optical-communications-optical-computers/