There are many ways to classify semiconductor lasers. On the basis of the wavelength can be divided into the far-infrared laser, near-infrared laser, visible laser, ultraviolet laser, and other categories. The blue semiconductor laser is a semiconductor laser whose output wavelength is in the range of 400 nm-500 nm.

Classification of blue laser:

• Blue light laser diode, usually using gallium nitride (GaN) and related materials, the wavelength range is 400-480nm, the output power can reach tens to hundreds of milliwatts.
• The helium-cadmium laser (gas laser) can radiate the light in the blue region of 441.6nm, the beam quality is very good, and the output power is several hundred milliwatts.
• High power optically pumped VECSELs, which are very suitable for frequency doubling laser light source with the output power of several watts or even tens of watts.
• Using optical fiber or crystal material thulium-doped or praseodymium doped upconversion laser radiation 480nm light, usually output power in dozens of milliwatts, and the beam quality is very good.

(5) Blue light or violet light can also be generated by laser frequency doubling (laser resonator) with wavelength 800-1000nm. For example, the 946nm neodymium yttrium aluminum garnet laser can achieve several watts of output power through frequency doubling, and its beam quality is also very good.

(6) Argon ion laser, using argon plasma laser amplification, is a very good laser light source. The power efficiency of the laser is very low and requires a large cooling device.

Application of blue laser:

Blue and violet lasers can be used in interferometers, laser printing and digital printing, data recording, laser microscopy, laser projection displays, flow cytometry, and spectral measurements. Recording data is the main driving force for the development of blu-ray laser diodes. In addition, copper materials are widely used in batteries, motors, power generation turbines, and some electronic components, and blue semiconductor lasers have great advantages in the processing of copper materials. If the future application process is mature, the demand for blue laser processing will be very considerable.