Ways of Seeing
Using Light in Unusual WaysA Conversation with Michal Lipson, Electrical and Computer Engineering
Little devices, including an all-optical switch, all-optical modulators, even cloaking devices—this is what the ability to manipulate light can yield. And Lipson has invented many little “light” devices for use in the microelectronics industry.
SNEAD: You actually manipulate light to make devices. How do you force light to make things?
LIPSON: Light usually likes to propagate in straight lines. So how do we tell light, “No, no, don’t go straight! Turn left. Turn right.” How do we distribute light? This is a very hard thing to do, especially at extremely small distances. Since light likes to go in a straight line, we can put it in a fiber, and then bend the fiber so very little that light doesn’t notice it’s bending.
Now, how do we make little devices? A lot of what I do is for computer applications. That’s chip scale. We use a special combination of two very different materials—oxide (basically glass) and silicon. These are the same materials used for microelectronics. It happens that this combination is fantastic for bending light.
Light always wants to travel in a straight line, unless we use this combination of materials to force it to bend. We etch down the silicon to form miniaturized fibers on the chip. About 10 thousand times smaller, the silicon fibers are now called the waveguide, and light travels through them. We actually make tiny tubes of silicon through which light travels, and we bend the silicon so that light stays in the silicon and travels around.
Once you know you can bend light using these special materials, what’s next?
Our goal is to make photonics or optics for applications in microelectronics, where they’re really needed. The microelectronics industry today is limited by heat dissipation. The industry can’t really increase the performance of next-generation computers because computers are getting hotter. But if we use light to propagate information, we can transmit a lot of information very fast with very low power dissipation. That’s our goal.
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