Blue, direct diode semiconductor lasers can be built using inorganic gallium nitride (GaN) or InGaN gain medium, upon which many (dozens or more) layers of atoms are placed to form the active part of the laser that generates photons from quantum wells. A blue laser emits electromagnetic radiation with a wavelength between 400 and 500 nanometers, which the human eye sees in the visible spectrum as blue or violet. Blue lasers can be produced by: Lasers emitting wavelengths below 445 nm appear violet, but are nonetheless also called blue lasers. As we will. CO2 laser engravers are a type of gas laser that use a mixture of gas to generate the laser beam. Argon-ion lasers, based on laser amplification in an argon plasma (made with an electrical discharge), are fairly powerful light sources for various wavelengths.
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