Dependence of Radiant Optical Magnetization on Material Composition

Abstract:

Discovering strong optical magnetism in nominally 'non-magnetic' media could lead to novel forms of energy conversion and the generation of large (oscillatory) magnetic fields without the use of current-carrying coils. By researching new nonlinear processes, we have the potential to do just that.

We report experiments and simulations of radiant optical magnetization in natural dielectrics at non-relativistic optical intensities. Our goal was to understand which molecular factors influence its magnitude. We studied centrosymmetric materials using ultrafast light scattering experiments in a 90-degree geometry, and compared the intensity dependence and spectra of the cross-polarized scattered light for several transparent liquids and solids.

The comparison of experimental results of scattering in different liquids agrees with quantum theory predictions of dependencies on molecular properties. In solids, the optically-induced magnetic scattering reached the same intensity as Rayleigh scattering, far below relativistic conditions. By comparing the spectra, we found that magneto-electric dynamics can account for unpolarized scattering from high-frequency librations, previously ascribed to all-electric processes.

Additionally, we present two theoretical descriptions. The first extends 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. Secondly, we show that the torque Hamiltonian of quantum theory obeys Parity-Time (PT) symmetry, indicating that magneto-electric effects should occur in all materials.