Instantaneous Reflectivity of Ni-Fe Alloy Single Layer Film and Its Composite Films with Different Thicknesses Excited by Femtosecond Laser

Ni-Fe alloy single layer film and its composite films with different thicknesses were deposited by magnetron sputtering technique.The influences of multi-layers and thickness on the instantaneous reflectivity of Ni-Fe alloy films were studied by using femtosecond laser pump-probe technology.The results show that the instantaneous reflectivity of Ni-Fe films arrived at the maximum after 0.2 ps excited by femtosecond laser,and then arrived at the minimum after another 0.2 ps,and the system was in equilibrium.The instantaneous reflectivity ΔR/R curves of the Ni-Fe alloy films had different changing ranges at zero.And the change values of ΔR/R curves after zero decreased first and then increased with the increase of thickness of Ni-Fe single layer film.