Metamaterials use composite resonators that can bend light any which way, potentially cloaking regions of space from visibility by diverting light around them. Now a mathematician has offered a blueprint for casting metamaterials into hollow fibers to create cloaked tunnels, each of which masks the light ascending from a planar pixel array to illuminate a 3-D display. By arraying the tiny cloaking tunnels in 3-D, light from the planar pixel array would travel up through the fibers unobserved except for their glowing ends, which would appear to be floating in space.
"Pass an object into one end, watch it disappear as it travels the length of the tunnel, and then see it reappear out the other end," said professor Allan Greenleaf, a mathematician at the University of Rochester.
Applying that principle to a 3-D display requires the light from planar arrays of pixels to travel up thousands of fibers to their assigned position in space. Being cast from hollow fibers made from metamaterials, ambient light diverts around the tunnels, making them invisible. Light from the planar array of pixels, on the other hand, travels unobserved up to each fiber's end, which is assigned a specific position in 3-D space. Arraying thousands of these pixels in space would enable 3-D displays to simply float in the air, according to the researchers.
Greenleaf and colleagues cautioned that 3-D displays using metamaterial tunnels is a long-term goal many years into the future, but that shorter-term applications could be found in medicine. For instance, metamaterial tunnels could mask the long endoscopic extensions that hold a surgeon's tool. By passing the tool through a metamaterial tunnel, surgeons could effectively hide everything but the tip of their tool from their vision, greatly facilitating quicker, more accurate endoscopic procedures.
Greenleaf and his collaborators have not yet constructed a metamaterial tunnel, but they claim to have created a mathematical blueprint for others to follow when constructing their own. In particular, a metamaterial needs to be designed with a negative index of refraction so that it can divert light from one side of the tunnel to the other, where it emerges as if the cloaked tunnel were not there.
The researcher's blueprint includes a variety of parameter settings for necessary metamaterial coating on the inside of the tunnels.
Greenleaf's collaborators include Matti Lassas, a professor at the Helsinki University of Technology; Yaroslav Kurylev, a professor at University College, London; and Gunther Uhlmann, a professor at the University of Washington.