Longitudinal Magneto-optical Effect Research Articles

Longitudinal magneto-optical effect enhancement with high transmission through a 1D all-dielectric resonant guided mode grating.

A significant enhancement of the longitudinal magneto-optical effect is demonstrated numerically and experimentally in transmission, and for small angles of incidence, through a subwavelength resonant structure consisting of a dielectric grating on top of a magneto-optical waveguide. The enhanced polarization rotation is associated with a high transmittance. These low footprint devices may thus be suitable for applications like magnetic field sensors or in non-destructive testing.

Mathematical Model of the One-stage Magneto-optical Sensor Based on Faraday Effect

The aim of this work is to refine a model of magneto-optical sensors based on Faraday’s longitudinal magneto-optical effect. The tasks of the study include computer modeling and analysis of the transfer characteristic of a single-stage magneto-optical sensor for various polarization of the input beam and non-ideal optical components. The proposed mathematical model and software make it possible to take into account the non-ideal characteristics of film polaroids observed in operation in the near infrared region and at increased temperatures. On the basis of the results of the model analysis it was found that the dependence of normalized transmission T(γ2) has periodic nature. Choosing the angle (γ2−γ1) makes it possible to shift the initial operation point and change the sensitivity dT/dγ2. The influence of the input beam polarization increases with the increase of polaroid parameter deviation from ideal and shows itself as reduction of modulation depth and angular shift of the sensor conversion response.

Experimental investigation on the magneto-optic effects of ferrofluids via dynamic measurements

An experimental investigation on the origin of the magneto-optic effects of ferrofluids is presented. Dynamic measurements of their transverse and longitudinal magneto-optic effects and their magnetic properties have been performed. As ferrofluids are colloidal suspensions of magnetic particles in a liquid, the influence of two parameters has been studied: the magnetic anisotropy energy of particles and the carrier liquid viscosity for four ferrofluid samples. The interpretation and the comparison of results give some clues for a better understanding of magneto-optical effects of ferrofluids.

Modification of the linear and nonlinear polarization dynamics in semiconductors owing to the Kerr magneto-optic effect

The contribution to polarization dynamics from a combination of linear birefringence, anisotropic nonlinear refraction, and a longitudinal magneto-optic effect is discussed. A Hamiltonian formalism is developed using Stokes parameters. It is found that by periodic reversal of the magnetic field, avenues are opened up to exploit Faraday rotation, for example, as an optical isolator, and polarization switching in an integrated optical environment. A practical implementation is discussed that uses semiconductors and a shaped-surface conductor.

Experimental investigation of longitudinal magneto-optic effects in four ferrite ferrofluids in visible-near infrared spectrum

We present an extensive experimental work concerning measurement of longitudinal magneto-optic effects (Faraday rotation and circular dichroism) induced in magnetic liquids. Seven ferrofluid samples allow the study of the influence of numerous parameters: magnetic suspension and carrier liquid characteristics, magnetic field strength (up to 10 kOe) and frequency (dc to 50 kHz), light wavelength (400 to 2000 nm) and, temperature (253 to 373 K). These topics, especially the spectral area, have rarely been studied before. Most of the studies show interesting behaviors and aid in the understanding of magneto-induced phenomena. They also contribute to the conception of new optical applications of ferrofluids: 1) a pure Faraday rotator (free of circular dichroism) obtained by a ferrofluid mixing method and 2) a Faraday light modulator working up to 50 kHz.

Nonreciprocal Magnetooptic Waveguides

The longitudinal magnetooptic effect can be used in a unique way to mix TE and TM modes of a planar dielectric waveguide where the strength of mixing is dependent upon propagation direction (forwards or reverse). A detailed study of Faraday effect circulators in optical dielectric waveguides is presented and accurate design data for a practical version are offered. At this writing, experimental confirmation has been hampered by lack of success optically contacting two dissimilar materials.

Longitudinal magneto-optical effect in Ni and nickel-rich Ni-Fe films in visible and near infrared regions

Magneto-optical properties of Ni and Ni-Fe films are studied experimentally for the spectral range 0.4 to 2.2 μ. From the measurement of longitudinal Kerr rotation and of optical constant of these evaporated films, the diagonal and off-diagonal components of the gyroelectric tensor are determined. The magneto-optical resonance is observed at a frequency of about 1 eV.

Polar and Longitudinal Magneto-Optic Effects in a Planar Geometry

The contributions of the propagation, impedance, and polarization perturbations to the magneto-optic effects in a lossless material are described. The general first-order characteristic matrices that include all three perturbations are formulated following the method of Smith for the polar and the longitudinal magneto-optic effects. Using the thin-film approximations, amplitude transmission and reflection coefficients are derived for a magneto-optic layer that is bounded by two nonmagneto-optic materials. The resulting coefficients are a simplified form of those given by Yoshino and Tanaka. These coefficients were expanded in a power series to show the nature of the multiple reflections within the magneto-optic layer. Because second-order terms are neglected, the thin-film approximation applies only to small total effects. The transmission and reflection coefficients are derived for the thick-film approximation and are compared with the thin-film approximation.

Contrast Dispersion in Magneto-Optic Apparatus for Domain Studies

A marked variation of contrast over the field of view has been discovered in apparatus for displaying domains by means of the Kerr longitudinal magneto-optic effect when convergent light is used to illuminate the sample. One of the effects seen is a rather dark central band parallel to the mean plane of incidence when polarizer and analyzer are crossed and one polarizes in the mean plane of incidence. Within this band there is no contrast between antiparallel domains, but on either side there is a region of strong contrast, and if a domain pattern is moved from one of these to the other its contrast reverses. The band of zero contrast moves at right angles to the mean plane of incidence if the polarizer is rotated, and tilting the sample gives a similar effect. Simple classical explanations of the effects are given, taking into account both metallic and Kerr ellipticities.