Sorry, Agent 007

Gregory Nemec

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It sounds like something James Bond would use to defeat a nemesis bent on world domination.

But the “anti-laser,” a new device created by Yale scientists, doesn’t defend against a laser attack; rather, it runs the principle of the laser in reverse. The laser, created in 1960, spits out waves of light with identical wavelengths—giving the beams the properties so useful to industry, law enforcement, and commerce. An anti-laser traps a laser beam, letting very little or no light escape. “It’s just like running a movie of the laser—backwards,” says Professor Hui Cao, one of the inventors.

Two years ago, Yale physicist A. Douglas Stone was struggling to describe to a colleague how a laser works and decided it was simpler to think in reverse. “As soon as I was done talking to him, I said to myself, ‘You know, I wonder if you could really do that, make such a device?’” Stone recalls. He teamed up with Cao and others to try. The results were reported in Science.

The anti-laser works by splitting a single laser beam into two, then running them both through a maze of mirrors so that they collide—and cancel each other out—inside a piece of silicon. There they can be transformed into another type of energy, such as heat or electrical current.

Why submit a beam of light to such torture? If the device were shrunk to microchip size, it could help make faster computers. It might also be used in photodynamic medical therapy, in which light’s energy could selectively heat and damage a tumor, for instance.

One thing the anti-laser can’t do is fend off Dr. No’s next attack—since it absorbs, rather than deflects, a laser’s energy. But not to worry. “A laser shield has already been invented,” says Stone. “It’s called a mirror.”