Blue laser

Additionally, gallium nitride (GaN) crystal layer construction proved difficult to manufacture as the material requires high nitrogen gas pressures and temperatures, similar to the environment for creating synthetic diamonds.

In 1992, Japanese inventor Shuji Nakamura, while working at Nichia Chemicals, invented the first blue semiconductor LED using an InGaN active region, GaN optical guide and AlGaN cladding, and four years later, the first low-power blue laser; eventually receiving the Millennium Technology Prize awarded in 2006, and a Nobel Prize for Physics along with Professor Isamu Akasaki, and Hiroshi Amano[7][8][3][9] in 2014 for this invention.

[10] The gain medium defects still remained too high (106–1010 defects/cm2) resulting in a low-power laser with a short, < 300 hour lifetime using pulsed excitation.

[11][12] In the late 1990s, Dr. Sylwester Porowski, at the Institute of High Pressure Physics at the Polish Academy of Sciences in Warsaw (Poland), developed technology to create gallium nitride mono-crystals with high structural quality using magnesium doping to create fewer than 100 defects/cm2 — at least 10,000 times better than prior attempts.

[13] In 1999, Nakamura used Polish-produced GaN crystals, creating lasers with twice the yield and ten times the lifetime of his original designs; 3,000 hours at 30 mW.

Using methods similar to those developed for silicon semiconductors such as the inclusion of doping materials (such as magnesium), the substrate can be built free of the type of defect known as dislocations and with uniform carrier distribution, allowing the gain medium atoms to be layered such that the distances between the atoms making up ground and those of the quantum wells are uniformly the same.

[17] The InGaN devices are perceived as significantly brighter than GaN (405) nm direct diode lasers, since the longer wavelengths are closer to the peak sensitivity of the human eye.

[21] Semiconductor lasers may be configured to emit photons either perpendicular or horizontal to the lasing medium layers depending on end use.