Dependence of Radiant Optical Magnetization on Material Composition

optical magnetization;nonlinear optics;magneto-electric scattering;ultrafast optics;dynamic magneto-optics;magneto-optics;Electrical Engineering;Physics;Engineering;Science;Electrical Engineering

Dreyer, ElizabethWinful, Herbert Graves ;

University of Michigan

关键词: optical magnetization;    nonlinear optics;    magneto-electric scattering;    ultrafast optics;    dynamic magneto-optics;    magneto-optics;    Electrical Engineering;    Physics;    Engineering;    Science;    Electrical Engineering;   

Others  :  https://deepblue.lib.umich.edu/bitstream/handle/2027.42/143980/efcloos_1.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

The realization of strong optical magnetism in nominally ;;non-magnetic” media could lead to novel forms of all-optical switching, energy conversion, or the generation of large (oscillatory) magnetic fields without current-carrying coils. By advancing understanding of radiant optical magnetization, the research reported in this thesis contributes progress toward these prospects.Experiments and simulations were performed of light scattering in natural dielectrics at non-relativistic optical intensities. The goal was to understand which molecular factors influenced the magnitude of induced magnetic dipole scattering in isotropic materials. The intensity dependence and spectra of cross-polarized scattering in several transparent molecular liquids (CCl4, SiCl4, GeCl4, SnCl4, SiBr4, TMOS, TEOS, TPOS) and crystalline solids (GGG, Quartz) were found to agree with predictions of quantum theory. Additionally, evidence was found for the expected proportionality between the intensity of radiant magnetization and the electric dipole transition moment, together with an inverse proportionality with respect to molecular rotation frequency. By comparing spectra in molecular liquids, it was found that spectral features in the cross-polarized scattering were uniquely attributable to high-frequency librations of magneto-electric (M-E) origin. In solids, optically-induced magnetic scattering in solids reached the same intensity as Rayleigh scattering, far below relativistic conditions. Additionally, all four channels predicted by the quantum theory for second-order (2-photon) M-E processes at the molecular level were observed in experiments on GGG crystals.Two theoretical contributions are presented in this thesis. The first is an extension of the classical Lorentz Oscillator Model from an atomic to a molecular picture. It includes the effect of torque exerted by the optical magnetic field on excited state orbital angular momentum, resulting in an enhancement in the magnetization achievable under non-relativistic conditions in molecular or condensed matter systems. Temporal dynamics are predicted for the first time, taking into account molecular composition. Secondly, the torque Hamiltonian of quantum theory is shown to obey Parity-Time (PT) symmetry, indicating that M-E effects should occur universally. Lastly, results from classical and quantum mechanical models are compared and found to be in very satisfactory agreement.