Zeev's Turnips Patch-No Politics (ZEEV)

[Shane]

Photonic Crystals in Uniforms
By TERESA RIORDAN


THESE may be lean economic times, but there is brisk demand for scientists who work on military projects.

One project is the $50 million contract the Defense Department gave earlier this year to researchers at the Massachusetts Institute of Technology. The goal is to build a sort of exoskeleton that among other things is supposed to give soldiers superhuman strength, protect them from biological and chemical weapons, and even help heal their injuries.

One of the researchers on the case is Yoel Fink, an assistant professor at M.I.T. Using, in part, technology he created, Mr. Fink and his team aim to embroider the supersoldier fighting uniform with polymer threads that — by selectively reflecting or absorbing different wavelengths of light — would silently flash an optical bar code. That way, for example, troops wearing specially tuned night-vision goggles would be able to distinguish between foe and friend during a night firefight.

The supersoldier project, officially known as the Institute for Soldier Nanotechnologies, has special meaning for Mr. Fink, who grew up in Israel and served in the army there.

"I spent three years of my life in the infantry," said Mr. Fink, who is now 36 years old. "It absolutely hits close to home because I know how vulnerable infantry soldiers are."

If two recently issued patents are any indication, though, Mr. Fink's ambitions extend beyond the battlefield.

Last month, Mr. Fink and several colleagues were granted United States Patent 6,463,200 for a fiber that steers light beams efficiently over long distances. The technology is being developed by OmniGuide, a start-up in Cambridge, Mass., that Mr. Fink co-founded and that recently secured $10 million in a second round of financing.

In August Mr. Fink received a more fundamental patent, Number 6,433,931, which broadly covers the use of certain polymers as photonic crystals — an innovation that Mr. Fink hopes will one day revolutionize optics the way the semiconductor revolutionized electronics.

As a tenure-track researcher at M.I.T. whose ideas are the foundation of a start-up company, Mr. Fink now seems a rising star. But when he first arrived at M.I.T. as a graduate student in 1995, he spent nearly a year and a half casting about for a project and a thesis adviser.

John D. Joannopoulos, a solid-state physicist at M.I.T. and expert on photonic crystals, did not take Mr. Fink into his laboratory. "He basically told me, `Look, I don't have any positions available,' " Mr. Fink said.

So when Mr. Fink came up with what he considered a revolutionary idea for building photonic crystals, he instead approached Edwin Thomas, a respected materials scientist at M.I.T. "I went to see him and said, `I want to talk,' " Mr. Fink recalled. Mr. Thomas said he could not talk because he was on his way to Greece.

Undaunted, Mr. Fink gave Mr. Thomas a copy of Professor Joannopoulos's book, to which Mr. Fink had stuck a yellow sticky note pithily outlining his idea. When he returned Mr. Thomas called Mr. Fink, eager to start working on the idea. Within a few weeks Mr. Fink had financing from the Air Force to pursue it.

For three months, Mr. Fink, Mr. Thomas and Tim Oyer, an M.I.T. patent lawyer, feverishly laid out a road map for developing the crystal. "We wanted to do with photons what people have been doing for years with electrons — to manipulate the flow of light in materials," he said.

Photons are the smallest known units of light, with both particle and wave properties. Photonic crystals allow for the manipulation of light.

Mr. Fink was by no means the only researcher trying to produce photonic crystals. "What struck me was that there wasn't a very good way to build these crystals," he said. "People were trying to build these structures by modifying semiconductor techniques."

While other researchers were trying to create photonic crystals by etching into silicon, Mr. Fink proposed a radically different idea: making a photonic crystal out of plastic.

The plastic he wanted to use was something called a block co-polymer, essentially a plastic made from two different types of polymers. Imagine one polymer as a string of pearls and the other polymer as a string of rubies, both of them loosely strung. Now imagine that when they are dropped into a jar and shaken, they self-entwine and pack themselves into a structure that repeats itself in a specific pattern — say, two rubies, four pearls, two rubies, four pearls and so on. "This a structure that forms itself," Mr. Fink said. "It doesn't require complicated processing."

In part it is this pattern, as well as the differing reflective qualities of the "rubies" and the "pearls," that gives this crystal such potential, Mr. Fink said.

Off the battlefield, how might life be different in the future if photonic crystals came to pass? Fashion mavens might leave the house in a turquoise outfit in the morning and retune the same outfit to tangerine when they went out to dinner. Optical communications systems might someday be woven into our clothing, making cellphones and hand-held devices seem like quaint artifacts of the early 21st century. And the innards of computers might rely as much on optics as on electronics.

Professor Fink has since won over Professor Joannopoulos, who ultimately became his thesis adviser and whom he now considers a mentor. But he acknowledged that though it had been proved experimentally, his self-assembling plastic photonic crystal project was still a long way from reality.

"It's a very beautiful idea," Mr. Fink said. "What's keeping us from flying with it right now is that we need a clever chemist — which I am not — to synthesize the polymer."

Mr. Fink says the first application to come out of his research is likely to be a light-transmitting fiber for a highly secure military communications network for the military. The main patron for his research, after all, is the Defense Department.

http://www.nytimes.com/2002/11/11/technology/11PATE.html

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