Nonthermal control of spins by short laser pulses is one of the preferable means to achieve ultrafast control of the magnetization in magnetic materials, representing a breakthrough in potential applications ranging from high density magnetic data storage, spintronics, to quantum information processing. Several Raman-type nonlinear optical processes have been exploited in optomagnetism to control the magnetic properties via laser pulses. In our method a harmonic of the frequency comb delivered by a multi-GHz infrared laser source is tuned to the Larmor frequency of a YIG (yttrium-iron-garnet) sphere to drive magnetization oscillations, which in turn give rise to a radiation field used to thoroughly investigate the phenomenon in a microwave cavity. Our findings demonstrate an effective technique for ultrafast control of the magnetization vector in optomagnetic materials via polarization rotation and intensity modulation of the incident laser beam. We also measure the value of the second-order nonlinear susceptibility underlying the process.
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