While lasers were invented in 1960 and are commonly used in many applications, one characteristic of the technology has proven unattainable. No one has been able to create a laser that beams white light.

Researchers at Arizona State University have solved the puzzle. They have proven that semiconductor lasers are capable of emitting over the full visible color spectrum, which is necessary to produce a white laser.

The researchers have created a novel nanosheet – a thin layer of semiconductor that measures roughly one-fifth of the thickness of human hair in size with a thickness that is roughly one-thousandth of the thickness of human hair – with three parallel segments, each supporting laser action in one of three elementary colors. The device is capable of lasing in any visible color, completely tunable from red, green to blue, or any color in between. When the total field is collected, a white color emerges.

The researchers, engineers in ASU’s Ira A. Fulton Schools of Engineering, published their findings in the July 27 advance online publication of the journal Nature Nanotechnology. Cun-Zheng Ning, professor in the School of Electrical, Computer and Energy Engineering, authored the paper, “A monolithic white laser,” with his doctoral students Fan Fan, Sunay Turkdogan, Zhicheng Liu and David Shelhammer. Turkdogan and Liu completed their doctorates after this research.