[CEATEC] 488nm Nonpolar Laser Demoed by Rohm, Looks Greenish

Oct 2, 2008
Tadashi Nezu, Nikkei Electronics
Rohm's demonstration. The laser on the right end is the nonpolar laser with a wavelength of 488nm.
Rohm's demonstration. The laser on the right end is the nonpolar laser with a wavelength of 488nm.
[Click to enlarge image]

Rohm Co Ltd exhibited a nonpolar laser whose wavelength is 488nm in a continuous oscillation. A nonpolar laser is a semiconductor laser that uses the nonpolar face of a GaN crystal.

"There have been 488nm semiconductor lasers developed by other companies, but they are rarely demonstrated," the company's spokesperson said.

Rohm has been working to develop a green semiconductor laser. The 488nm laser is not a green laser. But "it looks green rather than blue when you actually see it," he said.

The 488nm light looks blue in a picture taken by a digital camera, but it looks greenish to human eyes.

"With a wavelength of 485nm or longer, the light apparently becomes more green as the wavelength increases, even by as little as 1nm," the spokesperson said.

When the nonpolar face of a GaN crystal is utilized, it is theoretically possible to reduce the influence of piezoelectric field, which restricts InGaN-series semiconductor lasers from attaining a longer wavelength.

Manufacturers, universities and research institutions have been accelerating their research and development for creating the world's first green semiconductor laser.

Currently, there are no semiconductor lasers that directly emit green light. Existing green lasers employ an SHG element, for example, to convert the wavelength of infrared light emitted from a semiconductor laser.

Green semiconductor lasers are expected to be more cost effective and smaller in size compared with existing lasers that use the aforementioned methods.