Optically induced magnetization in homogeneous, undoped dielectric media

Abstract

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 CCl 4 , C 6 H 6 , and H 2 O 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.

Quantum theory of coherent transverse optical magnetism

“…The measured magnetic susceptibility can be as large as half the electric dipole susceptibility, even far from any electronic resonances. Classical theory [2] that accounts for these surprising effects through the leading term of the multipole expansion, and predicts many new magneto-optical phenomena, agrees with these observations. However a quantum mechanical analysis of transverse optical magnetism has not yet been provided.…”

“…Recently published experiments [1][2][3] and classical analysis [2] have revealed a quadratic mechanism whereby intense magneto-electric response can be obtained in (nominally nonmagnetic) dielectric media. Magnetic dipole emission nearly as intense as the electric polarization has been reported at infrared and visible wavelengths in transparent dielectric liquids (CCl 4 , C 6 H 6 , and H 2 O), far from any electronic resonances.…”

“…Research performed in transparent dielectrics (water, CCl 4 , and benzene) at optical intensities as low as I ϳ 10 8 W/cm 2 , fully ten orders of magnitude below the relativistic optics threshold of I ϳ 10 18 W/cm 2 , has now provided experimental evidence of a second-order magneto-electric optical process capable of generating intense magnetic dipole emission [1][2][3]. The measured magnetic susceptibility can be as large as half the electric dipole susceptibility, even far from any electronic resonances.…”

Dependence of optically induced magnetism on molecular electronic structure

“…The incident beam was the amplified, pulsed output from a Clark-MXR 2001 laser system, nominally consisting of 100 fs linearly polarized pulses at a repetition rate of 1 kHz. Measurements were performed using the same approach outlined in previous publications [1,2], except that the input power was varied using a precision-compensating wedge device to avoid beam deviation and nonlinearities from the intensity controller. Polarization of the input beam was controlled with a half-wave plate placed before the sample.…”

Fraunhofer-type absorption line splitting and polarization in confocal double-pulse laser induced plasma

“…Consequently, the role of the first-pulse LIP, besides creation of the rarefied cool outer shell exploited in DP-LIP [34], is its forming the special conditions (cloud of atoms and ions) required for the second laser pulse to generate a high magnetic field in the DP-LIP plume. Another explanation for a high magnetic field inside the plasma plume may be found in recently discovered strong magnetic dipoles generated by laser light passing through media which create high magnetic fields [43]. In either case, Fraunhofer-line polarization and splitting found in observation directions n v perpendicular π and σ planes in DP-LIP reveal the existence of a strong magnetic field in the earliest plasma life period.…”