Optically induced magnetization in homogeneous, undoped dielectric media

A widely held viewpoint in optics, namely, that dynamic magnetic effects are extremely weak at optical frequencies, is re-examined. Nonlinear charge motion induced by the optical magnetic field in dielectric systems is analyzed, is predicted to be resonantly enhanced, and is observed experimentally in CCl4, C6H6, and H2O at the fundamental input frequency. Excellent agreement is obtained with a classical magnetic harmonic oscillator model, which shows that the maximum dynamic magnetic dipole (MD) moment at optical frequencies is one half the electric dipole (ED) moment. As a consequence, magnetic dipole radiation generated by the optical magnetic field with an intensity one fourth that of ED radiation, as well as unanticipated nonlinear optical effects such as magnetic white-light generation, can arise in homogeneous transparent dielectrics. The mechanism of MD formation is confirmed experimentally to be second order in the input field, and the strength of the radiation is accounted for as a first-order contribution to the vector potential. Predictions are made of optical magnetic resonance, negative permeability, self-induced magnetic birefringence, and optically induced Faraday rotation. © 2008 Optical Society of America OCIS codes: 190.0190, 190.4410, 190.7710, 320.7110, 350.3618.