Rotational resonance of magnetoinductive waves: Basic concept and application to nuclear magnetic resonance

Published versio

Rotational resonance of magnetoinductive waves: Basic concept and application to nuclear magnetic resonance

Published versio

Magnetic response from a composite of metal-dielectric particles in the visible range: T-matrix simulation

The optical response of a particle composed of a dielectric core surrounded by a densely packed shell of small metal spheres is simulated with the superposition Tmatrix method for realistic material parameters. In order to compute the electric and magnetic particle polarizabilities a single expansion T-matrix is derived from a particle centered T-matrix. Finally the permeability of a medium comprising such particles is found to deviate considerable from unity resulting in a noticeable optical response

Electrical circuit model of arrays of resonant elements

We present an effective electrical circuit model that can be used for a quasianalytic analysis of electromagnetic oscillations in arrays of coupled elements, resonant in the microwave domain. The model accounts for electric and magnetic interactions between charges and currents excited in individual resonators. Respective coupling coefficients can be calculated from the field and current distributions in a subsystem of just one or two elements, provided by a finite-difference electromagnetic solver. The model was used to investigate current distributions and dispersion relations of wave propagation on chains of coupled split-ring resonators. The change of the dispersion characteristics from forward to backward propagating wave type observed experimentally is readily reproduced by the model

Perturbational estimation of geometry tolerances for rectangular integrated optics devices

Shifting the location of a dielectric boundary in the cross section of an integrated optical waveguide with piecewise constant refractive index profile results in a permittivity perturbation in a layer along the discontinuity line. On the basis of these thin layer perturbations, we discuss perturbational expressions for the derivatives of the propagation constants with respect to geometry parameters, both for fully vectorial, hybrid and for semivectorial approximations to the basic mode fields. The expressions are numerically verified by comparison with rigorously calculated data for a common semiconductor rib waveguide. Applied to a more complex device, the perturbational approach allows to estimate its complete set of tolerances for the geometry parameters, including the wavelength, on the basis of a single mode analysis. This is exemplified with a two rib waveguide coupler. By comparison with conventionally computed tolerances we give some assessment for the applicability of the effective perturbational approach

Integrated magnetooptic cross strip isolator

A bimodal planar waveguide segment of specific length and thickness between two thinner single mode sections can serve as an interferometer. Depending on the phase gain of the two modes in the thick region, these fields can interfere destructively or constructively at the transition from the bimodal to the single mode section. We employ this geometry to realize a simple magnetooptic isolator configuration, using a wide strip that is etched into a double layer in-plane magnetized magnetooptic film. The magnetization is oriented parallel to the strip; the light traverses the strip perpendicularly. Then the magnetooptic effect causes the phase velocities of TM polarized waves to be different for opposite directions of light propagation, resulting in a nonreciprocal power transfer across the strip. For a properly selected geometry one can expect isolator performance. If the strip width varies slightly, then adjusting the beam in-coupling position means to change the distance which the light travels in the two mode segment. This offers a convenient tuning possibility, which may be a means to overcome the strict fabrication tolerances that apply usually to interferometric integrated isolator concepts

Analysis of nonreciprocal light propagation in multimode imaging devices

We investigate a structure consisting of a magneto-optic multimode waveguide and two monomode waveguides serving as in- and outlets. The geometrical dimensions of the multimode waveguide can be adjusted such that the guided modes interfere constructively in forward direction and destructively for backward propagation. In this paper we present concepts for a circulator and two isolators based on multimode imaging

Interacting waves on chains of split-ring resonators in the presence of retardation

Wave propagation is studied experimentally in a one-dimensional periodic chain of magnetically coupled split-ring resonators with a spacing of about one tenth of the resonant wavelength. Retardation leads to a strong interaction between magnetoinductive and free-space waves. Two kinds of guided modes are observed: a slow backward wave which propagates far outside the light cone, and a fast forward wave close to the light cone. The two merge in a region of zero group velocity. The results are relevant for all one- and two-dimensional periodic systems interacting with waves of the surrounding space. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3462314