Theorists says anti-laser is possible

William Atkins
Friday, 06 August 2010 23:34

Science - Energy

A team of physicists has come up with a theory that conjectures one day an anti-laser could be built to absorb all the light that is comes into contact with, which is just the opposite of a real laser that amplifies light.

 

A theoretical description of the antilaser appears as an article, on July 26, 2010, within the journal Physical Review Letters.

The paper is entitled 'Coherent Perfect Absorbers: Time-Reversed Lasers.'

And, it is authored by Y. D. Chong, Li Ge, Hui Cao, and A. D. Stone, all from the Department of Applied Physics at Yale University (New Haven, Connecticut, U.S.A.).

They state as the abstract to the paper: 'We show that an arbitrary body or aggregate can be made perfectly absorbing at discrete frequencies if a precise amount of dissipation is added under specific conditions of coherent monochromatic illumination.'

'This effect arises from the interaction of optical absorption and wave interference and corresponds to moving a zero of the elastic S matrix onto the real wave vector axis. It is thus the time-reversed process of lasing at threshold.'

'The effect is demonstrated in a simple Si slab geometry illuminated in the 500-900 nm [nanometer] range. Coherent perfect absorbers act as linear, absorptive interferometers, which may be useful as detectors, transducers, and switches.'

In other words, the time-reversed laser, or anti-laser, absorbs light beams that are directed into the device, just the opposite of absorbing light as what the laser does.

A laser (LASER) is short for the term "light amplification by stimulated emission of radiation". It is a device that emits electromagnetic radiation, such as visible light, infrared, or ultraviolet radiation, through a process of stimulated emission.

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