Removing Reflections from Invisibility CloaksCategory: Science & Technology
Posted: November 12, 2012 06:37AM
Some years ago the first real example of fictitious invisibility was achieved by using metamaterials. These materials are completely man-made and take advantage of the physical laws that control light to make it do unnatural things. Those first cloaks though were not perfect but now researchers at Duke University have reduced the problems by tweaking the geometries.
Metamaterials for cloaking purposes work by directing light that would normally reflect off the device, thereby revealing it, around the shape, so it leaves without any information about the object. The imperfections of these first cloaks had to deal with reflections at their edges. As the researchers describe, the issue is similar to light reflecting off of a clear piece of glass; not major, but noticeable. To reduce these reflections the researchers shifted parts of the structure so that they met their mirror images. This way the light would be split in two, travel through the device, and then recombine into one beam with minimal loss.
While the experiment and calculations were done for metamaterials-invisibility-cloaks, the lessons learned from this could be applied to other optical technologies, including optical cable. At each bend of a fiber optic cable, some light is lost, causing the signal to attenuate. By adding some metamaterials it should be possible to smooth out the bends, to minimize the attenuation.