DIA Study: Invisibility Cloaking Theory and Experiments

Owing to the edgy shape of the stealth plane, most of the incident electromagnetic waves are reflected in different directions; the coating of the plane absorbs the rest. As light is simply an electromagnetic wave with shorter wavelengths than microwave radiation, one could imagine an optical cloaking device as the microwave cloak but with much smaller cells, fitted to the smaller wavelength. Second, and more important, the cells of a metamaterial also emit electromagnetic radiation in an incoherent way, not just as a coherent response to the incoming electromagnetic wave, similar to the spontaneous emission of light by atoms and molecules.

Source: publicintelligence.net