Light can be understood as a transverse electromagnetic wave composed of oscillating electric and magnetic fields. The orientation of the electric field in the light wave is described by the light’s polarization. Many light sources including sunlight, halogen lighting, and LED spotlights are considered unpolarized because the orientation of their electric fields fluctuates randomly in time. Laser sources, on the other hand, are often linearly polarized.
Polarization-Dependence of Reflectance
A single light wave consists of two independent, orthogonal components constituting the p- and s-polarization states, which are crucial in applications utilizing the reflection and transmission of certain polarizations of light. For p-polarized light, the electric field is parallel to the plane of incidence of an interface while the electric field is perpendicular to the plane for s-polarized light (Figure 1).
Figure 1: Depiction of s- and p-polarization, which are linear polarizations defined by their relative orientation to the plane of incidence. This figure also shows Brewster’s angle, at which no p-polarized light is reflected at an optical interface.1
