A single device that can emit laser light across the colour spectrum has been created by Arizona State University researchers

First white laser paves way for new applications

The first laser emitting white light has been created by American researchers paving the way for future applications including energy-efficient lighting and high-fidelity computer screens.

The device, described as a real breakthrough by its creators from Arizona State University, the USA, relies on a thin layer of semiconductor with three different segments supporting laser action in three elementary colour bands.

As a result, the laser can emit light over the full visible spectrum. It can be either tuned to emit different colours or cover the whole field at the same time which results in white light.

"The concept of white lasers first seems counterintuitive because the light from a typical laser contains exactly one colour, a specific wavelength of the electromagnetic spectrum, rather than a broad-range of different wavelengths,” said Cun-Zheng Ning, from the School of Electrical, Computer and Energy Engineering of Arizona State University and author of the invention described in the latest issue of the journal Nature Nanotechnology.

“White light is typically viewed as a complete mixture of all of the wavelengths of the visible spectrum."

While laser technology has been around since the 1960, serving in a multitude of applications, no one has so far managed to create a white laser.

The researchers believe the invention could pave the way for entirely new applications of laser technology. White lasers, they say, could replace LED lights and serve as a mainstream lighting source, which would be particularly beneficial due to their low energy requirements.

In addition to the energy efficiency, lasers are also brighter and can potentially provide more accurate and vivid colours for displays like computer screens and televisions.

Ning's group has already shown that their structures could cover as much as 70 per cent more colours than the current display industry standard.

Another important application could be in the future of visible light communication in which the same room lighting systems could be used for both illumination and communication. The technology under development is called Li-Fi for light-based wireless communication, as opposed to the more prevailing Wi-Fi using radio waves. Li-Fi could be more than 10 times faster than current Wi-Fi, and white laser Li-Fi could be 10 to 100 times faster than LED based Li-Fi currently still under development.



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