Polarization

Abstract

To understand how light propagates through a medium we need to know the basics of electromagnetic theory, polarization, reflection, and diffraction. In this chapter we shall address the principles of polarization. We shall consider the nature of polarization and how linear, circular and elliptical polarization states are just different aspects of the same rotation of the electric field as is best demonstrated by the Poincare sphere. Unpolarized light can be polarized by subjecting it to various physical effects which we shall consider. We then move on to describe how polarized light can be created. Polarization can be caused by a transmissive polarizing device, by reflection, by refraction or by scattering. The production of polarized light can result in linear, circular or elliptical polarization and also depends upon the nature of the light approaching the cause of polarization, e.g. randomly (or unpolarized) light, partially polarized and linear, circular or elliptical states of polarization. We also have the Faraday Effect where an electromagnetic field impinging upon an electromagnetic wave can cause polarization of the wave. Using, manipulating, and understanding polarization leads to many practical uses in the fields of biology, medicine, geology, astronomy and many other physical sciences including communications.