Blue laser

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:

• direct, inorganic diode semiconductor lasers based on quantum wells of gallium(III) nitride at 380-417nm or indium gallium nitride at 450 nm
• diode-pumped solid-state infrared lasers with frequency-doubling to 405nm
• upconversion of direct diode semiconductor lasers via thulium- or paraseodyium-doped fibers at 480 nm
• metal vapor, ionized gas lasers of helium-cadmium at 442 nm and 10–200 mW
• argon-ion lasers at 458 and 488 nm

Lasers emitting wavelengths below 445 nm appear violet, but are nonetheless also called blue lasers. Violet light's 405 nm short wavelength, on the visible spectrum, causes fluorescence in some chemicals, like radiation in the ultraviolet ("black light") spectrum (wavelengths less than 400 nm).