A semiconductor laser that is capable of emitting white light has been developed by researchers at Arizona State University [Fan et al., Nature Nanotechnology (2015) doi:10.1038/nnano.2015.149]. The device could provide a cost and energy efficient alternative to light emitting diodes (LEDs), while leading the development of faster wireless technology.

Lasers are considered to be the next light source as they light a wider color range and are more energy efficient than LEDs. A tiny single structure such as a semiconductor is ideal for application to mainstream lighting. Semiconductors are a solid chemical element or compound and produce a specific color of light when a volt is applied.

To produce white light, the visible spectrum of blue, green and red is necessary. However, semiconductors normally produce light of one color, depending on its atomic structure and energy bandgap, making it difficult to grow a single semiconductor material with the lasing capacity of all visible spectral range.

Cun-Zheng Ning and colleagues developed a nanosheet that is capable of emitting any visible colors as well as white color. It is made of a thin layer of semiconductor with three segments and is smaller than human hair in size and thickness.

To achieve this, Ning’s team looked at nanowires and nanosheets, based on the fact that structural differences between semiconductors for each color can be better tolerated at nanometer scales. First, they found that it is possible to grow nanowire materials which are tunable from red to green on a single structure. In order to gain the last color of blue, the researchers developed a strategy called dual ion exchange process, which allowed them to first create the shape and then organize the composition to emit the blue light.

The new structure could produce up to 70 percent more colors than the current display standard. Also, it is potential for the development of light based wireless communication (Li-Fi) which could be 10 times faster than Wi-Fi that is based on radio waves.

According to the researchers, the next step is to achieve running white lasers on a battery which would bring this invention closer to application in real-life technologies.

This paper was originally published in Nature Nanotechnology (2015) doi:10.1038/nnano.2015.149.