Coherent perfect absorber

A coherent perfect absorber (CPA), or anti-laser, is a device which absorbs coherent light and converts it to some form of internal energy such as heat or electrical energy. It is the time reversed counterpart of a laser. The concept was first published in the July 26, 2010, issue of Physical Review Letters, by a team at Yale University led by theorist Douglas Stone In the September 9, 2010, issue of Physical Review A, Stefano Longhi of Politecnico di Milano showed how to combine a laser and an anti-laser in a single device. In February 2011 the team at Yale built the first working anti-laser. It is a two-channel CPA device which absorbs the output of two lasers, but only when the beams have the correct phases and amplitudes. The initial device was able to absorb 99.4 percent of all incoming light, but the team behind the invention believe it will be possible to increase this number to 99.999 percent. Originally with the FP cavity, the optical CPA operates to a specific frequency and the wavelength thick material. In January 2012, thin film CPA has been proposed by utilizing the achromatic dispersion of metal, exhibiting the unparalleled bandwidth and thin profile advantages. This theoretical evaluation has been experimentally demonstrated in 2014.