It can be divided into three categories.
The first type: Thermal conductivity welding, refers to energy density less than 105w/cm² welding method. It is characterized by wide and shallow welding pool section.
The second type: Deep penetration welding, refers to energy density at 105w-107w/cm² welding method. It is characterized by a narrow and deep keyhole in the welded pool section welding.
The third type: MOPA laser welding, using the characteristics of high peak and short pulse of MOPA laser, This enables MOPA laser welding to be used for welding between two or more dissimilar metals with different melting points. It is characterized by sawtooth welding pool section. It also can be call "micro keyhole welding".