FUTURESPEAK

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AD: What do photonic crystals allow you to do?

JJ: They allow you to make things a lot smaller than before, so you have much better control. You can do things now that weren't possible before, like confining light in air. If you confine light in air, you lose less light. There's less scattering than with fiber optics, where the light interacts with the material it moves through.

AD: Where will photonic crystals be used?

JJ: There are lots of applications. In as little as 10 years, they could replace fiber optics and be used in phone lines and cable lines. The photonic crystals could make it possible to integrate a large number of components and devices on a chip. In contrast to nanotechnology, instead of making electronic devices on a very small scale, you're making optical devices on a very small scale.

AD: What's the advantage of doing that?

JJ: It allows you to do more things in a smaller amount of space and with less power.

AD: What needs to happen before photonic crystals are incorporated into the telecommunications infrastructure?

JJ: To commercialize it, engineers would have to prove that the fiber or tubing could be manufactured cheaply and would be durable. Then it has to be easily manufactured in a large scale operation [and] has to gradually fit in with existing systems. If you're replacing fiber, you want to connect its replacement to what exists already. If you're replacing devices, you want to ensure that you can connect to conventional fiber optics. You can't replace everything at once.

AD: What are other potential applications?

JJ: Because photonic crystals are very good reflectors or mirrors, you can use them to color food. You can make candy shiny or change the color of candy by incorporating the crystals, which can be designed to reflect only certain colors. Basically, you can color candy without using dyes. One candy manufacturer has already expressed interest in funding this research.

AD: How could microphotonics help us on the home front?

JJ: Microphotonics could help save energy. Because they reflect light, photonic crystals could be used to keep heat or light inside or outside of something. It could therefore cut heating or air conditioning bills. We could create a clear coating or paint that contains photonic crystals and works like thermal radiation insulation. You could paint the inside of your house or the insides of windows to keep heat in. If you applied it to the outside of your car, it would keep the heat out.

AD: What medical applications are possible with photonic crystals?

JJ: Photonic crystals could give you control over the time and place of drug delivery. Right now, if you take a drug it's in your entire bloodstream. It's active everywhere. If it's designed to kill cells, it kills more than just the tumor. That may not be the best thing when you want it concentrated at one spot. What if the drug was embedded in photonic crystals? The drug won't be activated until it passes through the intersection of two laser beams. By targeting where and when the drug is released, we could help people who have tumors or diseased organs, without adversely affecting healthy cells. Conceptually, we know this is possible.

JOHN JOANNOPOULOS

Like Prometheus, who tamed fire, researchers are harnessing light to do their bidding. By reining in otherwise uncontrollable particles of light known as photons, scientists intend to increase the rate at which information flows.

Breakthroughs in microphotonics, the technology that controls light on a microscopic scale, could not only turbo-charge data transfer, but also change how we insulate our homes, says John Joannopoulos, a physics professor at the Massachusetts Institute of Technology.

Fiber-optic cables currently used in our telecommunications networks move light through silica wire. But light sent through a solid scatters and diminishes in intensity. One solution is to guide light through air instead. But until recently, that was impossible to do because light, by nature, tends to flee air and escape into the walls of a fiber or tube.

Using one form of microphotonics, known as photonic crystals, Joannopoulos' lab has devised a way to trap light and guide it inside a fiber or hollow tube without danger of leakage. The photonic crystal material selectively reflects light of certain wavelengths and prevents the light from penetrating the walls of the hollow tube that confines it. In 2000, Joannopoulos cofounded Cambridge, Mass.-based Omni-Guide Communications, to use the technology to improve upon fiber optics. He recently spoke with American Demographics' Sandra Yin about photonic crystals' market potential.

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