Building invisibility cloaks starts small
Researchers in applied physics have cleared an important hurdle in the development of advanced materials, called metamaterials, which bend light in unusual ways. Working at a scale applicable to infrared light, the Harvard team has used extremely short and powerful laser pulses to create 3-D patterns of tiny silver dots within a material. Those suspended metal dots are essential for building futuristic devices like invisibility cloaks. The new fabrication process, described in the journal Applied Physics Letters, advances nanoscale metal lithography into three dimensions — and does it at a resolution high enough to be practical for metamaterials. “If you want a bulk metamaterial for visible and infrared light, you need to embed particles of silver or gold inside a dielectric, and you need to do it in 3-D, with high resolution,” says lead author Kevin Vora, a graduate student at the Harvard School of Engineering and Applied Sciences (SEAS). The optical table in...