Polarization 3.1 General Aspects

Abstract

An infinite plane wave in free space is transversally polarized which means that the electric field vector is always perpendicular to the direction ofwave propagationz. The electric field is thus characterized by its components in the x-direction and the y-direction. For natural light and for the majority of lasers, the field vectors change their orientations randomly and in a short time interval compared to the detection time. Light sources with these properties are called unpolarized. In the following we discuss completely polarized light which means that the electric field vector either points in a fixed direction or changes its orientation periodically. The polarization of an electromagnetic field is completely characterized by the components of the electric field E in the x-and the y-direction. The field vector can be written such that common phase terms in the x-and the y-direction are extracted: Fig. 3.1 The polarization of the electric field is characterized by the x-y-components field vector with the z-axis pointing into the direction of propagation. The polarization state is visualized in the x-y-plane by the projected curve traversed by the tip of the field vector. The field depicted is linearly polarized.