‘Anti-laser’ built for first time

by New Scientist:

In an anti-laser, or coherent perfect absorber, the outgoing laser beams are replaced by incoming ones, and light flows into a light-absorbing material instead of out of a light-amplifying one (Image: Science/AAAS)

An anti-laser – which absorbs light rather than emitting it – has been built for the first time.

A laser shines by producing a cascade of photons that bounce around inside a light-amplifying material before exiting from one or both ends. In 2010,Douglas Stone at Yale University and colleagues devised a way to reverse the process, with a material that absorbs rather than amplifies light.

The researchers chose the wavelength of the laser light so that light waves hitting the outside of the slab from the laser beams were in just the right phase with the waves transmitted through the material to trap the light inside the slab.

The silicon absorbed 99.4 per cent of near-infrared light with a wavelength of 998.5 nanometres, turning it into heat. “Theory and experiment matched very well,” says Stone. “We couldn’t have expected to do any better.”

Future computers may use light to transmit signals efficiently between their chip processors. Anti-lasers could be used to modulate the intensity of that light, or to convert light signals into electrical form for on-chip processing, the researchers say.

New Scientist

This kind of technology will lead to major improvements in computer developments and could play a key role in developing artificial intelligence.