Research On Photo-induced Needle Magnetization Field Regulation In All-optical Magneto-holographic Storage

Lasers have achieved important applications in many fields due to their unique properties.In the reason of its ultrafast nature,ultrashort laser pulses provide an effective tool for the research of fast magnetic recording.In 2007,Stanciu et al.used the amorphous ferromagnetic alloy Gd₂₂Fe_74.6Co_3.4 as the research object,and observed the rotation-dependent all-optical magnetic reversal phenomenon by using a 40fs circularly polarized pulsed light experiment.The fastest reversal time can reach 100ps.Therefore,a new field-all-optical magnetic storage has become the focus of attention.The helicity-dependent all-optical magnetic reversal is based on the Inverse Faraday Effect by changing the chirality of the circularly polarized input light.The magneto-optical material induces a stable light-induced magnetization field that is the same or opposite to the direction of the incident light.As the result,the electron spin-magnetic reversal can be realized without the aid of an external magnetic field.Magnetic holography,as one of the most important data storage method,has received widespread attention,but still has shortcoming,such as low resolving power,low diffraction efficiency and slow recording speed.In order to fundamentally solve the existing problems of current magnetic holographic storage,develop light-induced magnetization field regulation technology from the perspective of practical applications.It makes full use of the advantages of ultra-fast all-optical and magnetic reversal,change the existing magnetic holographic storage method and develop all-optical magnetic holographic storage technology based on the Inverse Faraday Effect,and develop light-induced magnetization field regulation technology.From the perspective of practical applications,develop light-induced magnetization field regulation technology to fundamentally solve the existing problems of current magnetic holographic storage.The main research work is as follows:1.Aiming at the problem of low resolution in magnetic holographic storage,through the control of the vector optical focus field,the sub-wavelength-resolved magnetic spot is produced through high numerical aperture focusing,which can increase the magnetic holographic recording density.Therefore,the vector light tight focusing theory and the Inverse Faraday Effect principle under high numerical aperture are introduced,and several vector light-induced magnetization field distribution characteristics are numerically simulated and summarized.2.Aiming at the problem of low diffraction efficiency in magnetic holographic storage,based on the theory of electric dipole radiation anti-diffraction,a high-purity light-induced magnetic needle is designed as a field source that can fully interact with the magnetic recording material,thereby improving the diffraction efficiency of magnetic holography.3.Aiming at the problem of low recording speed in magnetic holographic storage,a magnetic needle array parallel recording is proposed since the point-by-point recording is time-consuming.Based on the theory of electric dipole radiation anti-diffraction,a single magnetic needle is extended to a magnetic needle array,through parallel recording of 4magnetic needles as an array and a total of 16 arrangements are possible,which improves the recording speed.