One of the uncomfortable realities about solar power is it simply lets too much of the energy delivered to it as photons get away, either reflected back or lost to entropy through waste heat and the like. Steady improvements have continued for years now, helping to alleviate, but not remove, the problem. But what if there were another way? Two scientists at Purdue proposed a method of building a tabletop 'black hole' that would trap electromagnetic waves. Less then a month later, scientists working in Nanjing, China created the device by using meta-materials that allow them the mimic the properties of cosmological black holes and create a 'battery' for light, a machine that has an event horizon past which light can not escape back out but remains.
The device is made of 60 layers of different metamaterials that are then covered in copper and "etched with intricate structures whose characteristics change progressively from one strip to the next, so that the permittivity varies smoothly."
Gizmodo quotes the teams explanation of what that translates to:
"When the incident electromagnetic wave hits the device, the wave will be trapped and guided in the shell region towards the core of the black hole, and will then be absorbed by the core," says Cui [one of the inventors]. "The wave will not come out from the black hole." In their device, the core converts the absorbed light into heat.
The fact that a working device for light with wavelengths in the microwave part of the spectrum was demonstrated so quickly after the idea was formulated and presented came as a surprise even to the lab rats who first proposed it, even though more challenges remain ahead for the technique:
Narimanov is impressed by Cui and Cheng's implementation of his design. "I am surprised that they have done it so quickly," he says.
Fabricating a device that captures optical wavelengths in the same way will not be easy, as visible light has a wavelength orders of magnitude smaller than that of microwave radiation. This will require the etched structures to be correspondingly smaller.
As useful as these creations will be for many, many purposes, solar power may be the biggest beneficiary. New Scientist focuses on that for us:
An optical black hole would suck it all in and direct it at a solar cell sitting at the core. "If that works, you will no longer require these huge parabolic mirrors to collect light," says Narimanov.
A couple notes for the skittish here. One, it's not a real black hole, its an analog. Second, even if it were, it wouldn't have the mass to do anything destructive like consume the earth. Black holes don't have more 'sucking' power then normal gravity. If the sun turned itself into a black hole right now the earth's orbit wouldn't change a lick, and would probably even widen slightly (the collapse into a black hole is catastrophic and the star blasts away a significant amount of its mass (and hence gravity) in the process). Cosmic waves interacting with the matter of the earth and our atmosphere are thought to create microscopic black holes frequently that are to small to remain stable and evaporate away.
Article links in the diary, two links to abstracts of the journal papers here. Worth the 24 dollars the article costs if you don't have access to a college that ponies up the big bucks for an electronic subscription to the journals.