Non-metallic mirror shows promise for new optoelectronic devices

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A new type of mirror that reflects infrared light using the magnetic property of a non-metallic metamaterial rather than a shiny metallic surface, has been developed by scientists at Sandia National Laboratories in Albuquerque, New Mexico, USA.

The mirrors have potential for use in new classes of chemical sensors, solar cells, lasers, and other optoelectronic devices. The work was reported in the Optical Society’s journal Optica.

The mirror was made from a non-metallic surface studded with nanoscale cube-shaped resonators based on the element tellurium. Each resonator is smaller than the wavelengths of infrared light, which is essential to achieve magnetic-mirror behaviour at these short wavelengths.

‘The size and shape of the resonators are critical,’ explained Sandia scientist Michael Sinclair, co-author on the paper, ‘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.’

Conventional mirrors reflect light by interacting with the electrical component of electromagnetic radiation. This reverses light’s electrical field, which has major implications in physics, especially at the point of reflection where the opposite incoming and outgoing electrical fields produce a cancelling effect. This prevents components like nanoscale antennas and quantum dots from interacting with light at the mirror’s surface.

A magnetic mirror, in contrast, reflects light by interacting with its magnetic field, preserving its original electrical properties. ‘A magnetic mirror, therefore, produces a very strong electric field at the mirror surface, enabling maximum absorption of the electromagnetic wave energy and paving the way for exciting new applications,’ said Sandia scientist Igal Brener.

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Sandia National Laboratories