The anti-laser—a tech with such a cool name it doesn't need an obvious application—first came to our attention last year when Yale's A. Douglas Stone proposed the idea. Now Stone is back with the real thing. His new paper in Science documents the world's first anti-laser.
Conventional lasers create intense beams of light by stimulating atoms to spit out a coherent beam of light in which all the light waves march in lockstep. The crests of one wave match the crests of all the others, and troughs match up with troughs. The anti-laser does the reverse: Two perfect beams of laser light go in, and are completely absorbed. [Wired]
Anti-lasers are a bit of a funny concept, because anybody who has worn black on an August afternoon knows that absorbing light
and turning it into heat isn't a problem. But creating a device that matches the concentrated beam of a laser and traps more than 99 percent of it—essentially reversing a laser—is an engineering feat. Whereas a laser
uses mirrors to bounce light back and forth through an amplifying material to concentrate it, the anti-laser, as the name would suggest, does basically the opposite.
The difference in the anti-laser is that instead of using an amplifying material, it uses one that absorbs it — or a "loss medium." After his research team did the math, Stone said, they decided that silicon was the best choice. The anti-laser is set up to split a single laser beam into two and direct the two beams to head toward each other, meeting at the paper-thin silicon wafer. The light's waves are precisely tuned to interlock with each other and become trapped. They then dissipate into heat. [Los Angeles Times]
The fact that Stone's team created a anti-laser so quickly after theorizing it isn't the only surprise. Another is that nobody had thought to do it until so recently.
The reversal experiment is exciting because nobody had thought of it before, says Marin Soljačić, a physicist at the Massachusetts Institute of Technology in Cambridge. "It is surprising to have something so new and quite fundamental discovered in such a mature field," he says. [Nature]
The creators aren't sure exactly what to do with this new toy. But as the Los Angeles Times
points out, the same was true of the laser upon its invention in the 1960s, and now supermarkets and Lasik clinics couldn't live without it. Related Content: 80beats: “Anti-Laser” Would Absorb the Light a Laser Shoots out
Image: Science / AAAS