Physical mechanisms of ultrashort pulse laser induced melting in copper

The kinetics and microscopic mechanisms of ultrashort laser melting of a copper film is studied by modified molecular dynamics method. A model considering the thermal conductivity of free electrons and the consumption of latent heat of melting is used to make the simulation more realistic. The mechanism responsible for the melting of copper under picosecond laser pulse irradiation can be attributed to the homogeneous nucleation of the liquid phase inside the solid region. The melting is a overheated melting caused by homogeneous nucleation, and the velocity of propagation of “melt front” is found up to be 5.8 nm/ps. Picosecond laser pulse induced melting occurring under the condition of thermal confinement results in a less complicate temperature distribution and a weaker effect of unloa