Scientists develop ‘anti-laser’

Researchers at Yale University have developed a device that can extinguish a laser beam. The ‘anti-laser’ can also be built in silicon, which makes it easier to use in optical computers.

The anti-laser not only absorbs the light of a laser, it has a completely opposite effect compared to a conventional laser. Light is generated therein and light of a specific wavelength is amplified in an optical resonator and transmitted on one side of the ‘optical cavity’. This results in a coherent light beam with a specific wavelength. The anti-laser developed by the scientists at Yale University developedthat coherent beam can absorb light and dissipate the energy as heat.

The antilaser, called ‘coherent perfect absorber’ or CPA by its discoverer, consists of an optical resonator, just like a laser. It is produced in such a way that light of a certain wavelength is captured and bounced back and forth in the resonator, just like a laser. Over time, however, this does not amplify the light, but rather absorbs the energy. The theoretical absorption of the CPA would be 99.999 percent of the incident light. The CPA for near-infrared light developed by the researchers achieved an absorption of 99.4 percent. Yale’s prototype CPA is still about one centimeter in diameter, but it could be reduced to six micrometers.

The energy that is absorbed is dissipated as heat. At the moment this heat cannot be used. However, that would be different with medical treatment methods. The principle of CPA could then be applied for radiotherapy or as an imaging technique. The anti-lasers could also be used in optical computers; they could serve as optical switches or photo detectors.