Scientists at Yale University claim to have developed an "anti-laser." The device, created by a Yale team including Dr. Douglas Stone, takes the laser concept in reverse: In a normal laser, the beam is created by feeding light or electricity through a gain medium like gallium arsenide, with reflectors positioned to keep the beams bouncing through. As the light bounces back and forth, the medium adds more photons to the mix (which is why it's called a "gain" medium), and one of the reflectors is partially transparent to let the amplified beam through-the laser.
In Stone's anti-laser device, the structure is similar, with two important differences: the incoming laser is countered with a beam that's the opposite of itself, and the medium, silicon, is optimized to be make the beam experience a loss of coherence rather than a gain. The result is that the two beams dissipate in the medium and the energy is released as heat.
Full story from PC Magazine
A dazzling show inside a laser, but a vacuum of light outside (New York Times)