Hidden magnetic effect of light could make solar power without solar cells possible
15 Apr 2011
A dramatic and surprising magnetic effect of light discovered by University of Michigan researchers could lead to solar power without traditional semiconductor-based solar cells.
The researchers found a way to make an ''optical battery,'' said Stephen Rand, a professor in the departments of Electrical Engineering and Computer Science, Physics and Applied Physics.
In the process, they overturned a century-old tenet of physics.
''You could stare at the equations of motion all day and you will not see this possibility. We've all been taught that this doesn't happen,'' said Rand, an author of a paper on the work published in the Journal of Applied Physics. ''It's a very odd interaction. That's why it's been overlooked for more than 100 years.''
Light has electric and magnetic components. Until now, scientists thought the effects of the magnetic field were so weak that they could be ignored.
What Rand and his colleagues found is that at the right intensity, when light is traveling through a material that does not conduct electricity, the light field can generate magnetic effects that are 100 million times stronger than previously expected. Under these circumstances, the magnetic effects develop strength equivalent to a strong electric effect.