Next50
Practical semiconductor lasers have been developed for red and blue, two of the three primary colors, but no semiconductor laser has yet been developed for green, the third primary color. Instead, a modified wavelength of infrared light is now being used as a green laser. This method, however, is associated with high energy consumption and is difficult to miniaturize.
ROHM has developed a non-polar (m surface) gallium nitride (GaN) crystal-growing technology that has been considered the single best structure for the green semiconductor laser. Difficulties with growing crystals, however, had delayed successful development. However, ROHM has used this technology to develop a pure blue (460 nm) semiconductor laser and has successfully maintained its continuous oscillation at room temperature, an industry first. This achievement is clearly a significant advancement in the development of a green semiconductor laser.
The eventual successful development of a green semiconductor laser will make available all three primary colors, which will make possible their application to a super-small full-color display. For example, super-small projectors can be incorporated in mobile phones. Their application in next-generation large-screen laser TVs with higher resolutions and wider color reproduction range can also be expected.
Improved efficiency and increased output are also issues in LED development. Application of ROHM's crystal-growing technology for non-polarized (m surface) gallium nitride greatly improves the possibility of developing a high-luminosity green LED and yellow LED.
Today, the backlights used in LCDs are merely lights deflected through a polarizing plate. One characteristic of a non-polar (m surface) GaN LED is that the emitted light is itself deflected. Its utilization results in a compact and highly efficient backlight source for LCDs. For this reason, this technology is drawing significant attention.
