New and Improved Lasers! Now in White
After the invention of laser technology in the 1960s, every cat knows that lasers come in single colors, usually red, green, or violet. This is because different kinds of semiconductors emit different colors of light and are difficult to combine to create color combinations. This limitation means that white lasers were impossible as it was impossible to produce light across the full color spectrum simultaneously.
Was being the operative word. Researchers at Arizona State University have developed a tiny (one-fifth of a human hair) sheet just nanometers thick (one one-thousandth of a human hair) with three segments rich in certain elements that produce specific colors of light. Cadmium and selenium-rich segments create red light, cadmium and sulfur segments produce green light, and zinc and sulfur segments give off blue light. A beam of light can be targeted at a specific part of the sheet, producing an array of colors never before possible, and including white, making it possible to finally produce a white laser.
The sheet was carefully developed in phases, to allow for specific heating and cooling temperatures to incorporate the various elements without risking system failure.
The key was producing a semiconductor small enough that an observer could perceive the light as a single color, white, and not the three color components required to create white.
So what? Without overstating the potential, white laser technology is a potential candidate to replace LEDs as a mainstream light source. As brighter, more accurate points of light, white lasers could provide efficient lighting and more accurate display screens. Even farther down the road is the concept of Li-Fi, light-based wireless communication that could take the place of radio-based Wi-Fi. Laser-based Li-Fi could be up to 10 times faster than Wi-Fi and 100 times faster than the LED-based Li-Fi that is presently under development.
This work is at the proof-of-concept stage, more research is required to have a functioning model under battery power that could be sustainable for light-source or display purposes.
The results of this research was recently published in Nature Nanotechnology.
Image credit: ASU