The nonlinear optics of magneto-optic media

by Jonsson, Fredrik

Magneto-optics is the discipline in physics concerned with the interaction of optical waves with matter under in uence of magnetic elds. The introductory part of the thesis develops a consistent treatise of the fundamentals of magneto-optical light-matter interactions. The original research of this thesis presents theoretical studies for two groups of nonlinear optical phenomena, within the coexistence of linear and nonlinear magneto-optical interactions. The rst group of studies in nonlinear optics focus on the third and fourth order optical and magneto-optical interactions governing optical Kerr-e ect and photoinduced Faraday rotation. A Fabry-Perot interferometer lled with a magneto-optic dielectric, possessing optical Kerr-e ect, is studied in the Faraday con guration under the action of a static magnetic eld, in whose presence linear and photoinduced Faraday rotation appear. It is shown that by exploiting the nonreciprocity of the magneto-optical interactions of the medium, the cavity shows a multistable behaviour at constant input light intensity, opening for a polarization state controlled switching device, being tunable by means of the static magnetic eld. Furthermore, unidirectional wave propagation in nonlinear magneto-optic media being anisotropic in the nonlinear regime is studied. The evolution of the polarization state of the beam is presented in terms of closed trajectories on the Poincare sphere, in a reduced Stokes vector description, and solutions for the corresponding eigenpolarizations are presented. The second group of studies in nonlinear optics focus on the second and third order optical and magneto-optical interactions governing the process of parametric generation. Optical parametric interactions of unidirectionally propagating elds are studied in magneto-optic media, in the Faraday con guration. In the analysis, rst and second order optical interactions and second and third order magneto-optical interactions are taken into account in the constitutive relations and subsequent wave propagation. It is shown that phase-matching can be obtained for circularly polarized elds by exploiting the arti cially induced gyrotropy of the medium. The theory of a magneto-optical parametric oscillator is presented, in a large-signal regime, for a singly resonant con guration. The pump threshold intensity and intracavity signal-to-pump ratios for circularly polarized waves are presented as functions of phasemismatch, and it is shown that tunable phase-matching can be obtained by means of varying the externally applied static magnetic eld. The studies presented in the thesis open for applications within the elds of optical switching and logics, and provide novel schemes for phase-matching in optical parametric ampli cation and oscillation.