Metal-covered cloaked device “sees without being seen”

To conceal an object, it might be common sense not to put it under shiny materials; but according to a study, that is exactly what one must do to make it invisible.

U.S. scientists have developed a virtually invisible photodetector by covering it with reflective metal, Science Daily reported Monday.

Researchers from Stanford University and the University of Pennsylvania found that by covering the device’s silicon nanowires with a thin layer of gold, a de-purification process called doping, they were able to make the reflective lights from the two materials cancel each other out.

The process starts with the silicon emitting oscillating electric currents, which then produce scattered light waves from the gold and the silicon. The light waves create a separation of positive and negative charges in the materials called a dipole moment.

When dipoles in the metal and the semiconductor are equally strong but have opposite poles, they cancel each other out. Since an object is visible through light that reflects off it, this allows the object to become invisible.