TEACHING THE PROPAGATION OF ELECTROMAGNETIC WAVES IN CHIRAL MEDIA BY USING TIME-DOMAIN SIMULATORS

The behavior of electromagnetic waves in a chiral medium is characterized by the appearance of the optical activity. The optical activity is the ability to rotate the polarization plane of a wave as it propagates in a medium. This phenomenon was first observed by Arago in 1811 while working with quartz crystals. In 1848, Pasteur demonstrated the relationship between the optical activity of some compounds and the existence of a specific kind of symmetry in its molecular structure. This symmetry was called chiral, that comes etymologically from the Latin word for hand, since it is the type of symmetry or our hands.

Since, molecular dissymmetry produces rotation of the polarization plane at optical frequencies, by scaling the problem, artificial chiral media for microwave frequencies were synthesized including small particles with chiral symmetry into a resin matrix. Nowadays, artificial chiral media have attracted considerable attention due to their new potential applications in millimeter-wave and microwave engineering becoming a relevant topic in science and technology.

In general, students have difficulty in perceiving the behavior of electromagnetic waves. The situation is worsened when chiral media are involved, since they exhibit complex electromagnetic phenomena such as optical activity, circular dichroism…
The aim of this work is to provide aid in the teaching of the typical physical phenomena occurring in chiral media by offering the students a mental image of the electromagnetic phenomena. To this end, we have used an extension of the Finite-Difference Time-Domain technique for modeling the wave propagation of the electromagnetic waves in chiral media to carry out a series of virtual experiments. These experiments have been carefully chosen to illustrate the characteristic behavior of electromagnetic waves in chiral media. The results of the simulations have been recorded and a collection of videos has been created.

These videos are intended for advance undergraduate and graduate students and provide a useful teaching/learning tool. We consider that by means of its visualization students will acquire a better conceptual understanding of the wave propagation of the electromagnetic waves in chiral material.