Magnetic Mirrors Light the Way for New Technologies

Mirrors in the real world can sometimes behave in surprising and unexpected ways, and one recently developed magnetic mirror is doing just that, lighting the way for new infrared technologies.

This new device forgoes a familiar shiny metallic surface and instead uses a magnet to reflect infrared light - wavelengths slightly longer than those visible by the human eye.

By placing nanoscale antennas at focal points of tiny magnetic reflectors, scientists have successfully harnessed electromagnetic radiation in ways that can lead to new classes of chemical sensors, solar cells, lasers, and other optoelectronic devices.

"We have achieved a new milestone in magnetic mirror technology by experimentally demonstrating this remarkable behavior of light at infrared wavelengths. Our breakthrough comes from using a specially engineered, non-metallic surface studded with nanoscale resonators," Michael Sinclair of Sandia National Laboratories, and co-author of a paper detailing development of the magnetic mirror, said in a statement.

Conventional mirrors reflect light by interacting with the electrical component of electromagnetic radiation. This form of energy, when it reflects off physical mirrors, reverses both the image as well as the electrical field. Though, this reversal has no effect on the image, as seen by the human eye. However, at the exact moment of reflection, waves cancel each other out, negating the electrical field of light at the surface of the mirror. This prevents tiny nanoscale antennas from functioning just above a physical reflector.

The new magnetic mirrors interact with the magnetic function of the wave, leaving electrical fields unaffected.

Non-metallic dielectric resonators were the key to the development of these magnetic mirrors. Tellurium, a metalloid element resembling tin, was used as the basis of the new device. The material is far more efficient than fish-scale devices at reflecting infrared waves, and is also easy to manufacture using standard technology.

"The size and shape of the resonators are critical, as are their magnetic and electrical properties, all of which allow them to interact uniquely with light, scattering it across a specific range of wavelengths to produce a magnetic mirror effect," Sinclair explained.

The device's design is detailed in the journal Optica.