Light has electric and magnetic components. Until now, scientists thought the effects of the magnetic field were so weak that they could be ignored. Stephen Rand and colleagues, University of Michigan, USA, have show that this is not true and, in the process, have developed an optical battery.

The team have shown that light can generate magnetic effects that are 100 million times stronger than previously expected when it travels through a non-conductive material. At high intensities of light, the magnetic effects can equal those of a strong electric effect. The team applied this effect to create a capacitive power source in which charge separation is induced by the magnetic field of light rather than the electric field. This could eliminate the need for semiconductors in solar cells, making them cheaper and more efficient.

• Optically-induced charge separation and terahertz emission in unbiased dielectrics
  W. M. Fisher, S. C. Rand,
  J. Appl. Phys. 2011, 109, 064903.
  DOI: 10.1063/1.3561505