Researchers have studied ultrafast non-equilibrium magnetization in correlated spin systems in recent years. At both fundamental and application levels, ultrafast laser pulse excitation and dynamics measurement provide an effective path to fast optical detection, as well as control of magnetic order. Studies have been conducted with magnetic media measuring the time-resolved magneto-optical Kerr effect (TR-MOKE), ultrafast magnetic relaxation phenomenon such as ultrafast demagnetization and uniform precession. The optically excited magnetization precession in magnetic media exhibits the temporal response of magnetization when the effective magnetic field is instantaneously changed by ultrafast laser pulse excitation and provides information about the spin dynamics microscopically.