Who Invented the Green Laser Diode?

The green diode laser was developed in 2009 at Semiconductor Technologies R&D Laboratories at Sumitomo Electric Industries, a Japanese company, and is not yet on the market. Green laser pointers do not use true green diode lasers, but instead produce green light indirectly.

Laser Color

• The color of a typical laser is determined by its material; helium-neon lasers are red, while argon ion lasers are blue. Diode lasers work somewhat differently; their color is determined by the energy difference between two or more semiconductor materials sandwiched together.

Problems with Green Lasers

• There are two reasons green lasers were invented so long after red and blue lasers. One of the materials required in a green laser is indium, which is very difficult to form alloys with; it usually diffuses and pools together, disrupting the carefully designed structure necessary for the laser. Gallium nitride is also necessary, but it normally carries an electric charge which disrupts the laser. Researchers discovered a way to make gallium nitride without an electrical charge, and presumably solved the indium problem as well.

How Green Laser Pointers Are Made

• Green laser pointers contain an infrared diode laser which powers another infrared laser. The laser is shone through a crystal which halves the wavelength of the light, creating green laser light around 530 nanometers in wavelength. These lasers are less than a fifth the efficiency of normal laser diodes.