The perfect coherent absorption, observed for the first time 3 years ago in a silicon slab, has attracted a great interest in the scientific community because from a theoretical point of view it is the reverse of the laser: in fact it gives rise to a device that absorbs the light completely, contrary to the laser which generates it. In general the absorption of light by a material depends on its dielectric properties and increases in proportion to its thickness. However, when not one beam but two coherent beams are impinging on a material, this may result in a phenomenon of interference that either completely eliminates absorption (perfect transparency) or makes it total (perfect absorption), regardless of the properties of the material.
In an article published in Nature Physics 10, 830-834 (2014) researchers from the laboratory Nest of the Nanoscience Institute of CNR (CnrNano) and Scuola Normale Superiore, in collaboration with colleagues from IFN-CNR and IOM-CNR, showed that it is possible to realize coherent perfect absorption, a complex phenomenon similar to a 'laser in reverse', in a class of nanostructures which has never before been tested for this phenomenon, in which matter and radiation are inextricably linked.
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