Last July some Japanese newspapers, including the Nikkei, carried articles on our novel technology, announcing that Sumitomo Electric has successfully developed the world’s first pure green semiconductor laser. Have you red any news on that?

Light's three primary colors (red-green-blue) are the source of all the other colors. Since the development of red laser in 1985 and a decade later, blue laser in 1996, the last green laser technology has long been expected to arrive. As the competition increasingly heated up in gallium nitride (GaN)-based green laser development, engineers ran into a snag called “green gap,” a sharp drop in lasing efficiency at 500 to 600 nm wavelength.

At Sumitomo Electric, we have overcome this problem by developing a GaN crystal which inhibits the efficiency drop, resulting in pulse operation of a laser diode emitting in the pure-green region at 531 nm. It is the first green laser diode in the world. Furthermore, we have even realized continuous wave operation at 520 nm.

To make it simple, please refer to the video below. The LED using conventional technology (at right) drastically turns into blue as a current flows in, while the light from a newly-developed GaN-crystal LED (at left) remains green. Can you see the difference?

Generally, green laser has been generated by converting infrared laser light with some optical material. However, our developed green laser, directly emitted from a semiconductor, requires less mechanical parts, thereby enabling reduction in size and cost. These advantages make the technology promising for the use in high-end displays and other wide applications.

I have repeatedly emphasized the importance of working closely among the R&D, sales and business sections to capture the needs of markets. Also, I have advised our people to get ahead of social changes and technical trends, and then to plan tasks with an eye on the clock and the goal. We are finally feeling some positive results from these efforts.

As part of the Group’s mid-term business plan “VISION 2012,” Sumitomo Electric has scheduled to invest 400 billion yen in its research and development in the 2008 to 2012 period. This year, despite an economic slump, we have devoted 73 billion yen to our R&D activities, expecting a great outcome. With such sufficient R&D budget, we will strive to conceive new products which may account for as many as 30% of whole company sales.

■Press release: Sumitomo Electric Develops The World’s First Pure Green Semiconductor Laser