2 - Basics of light guidance

Abstract

The understanding of the physical principles of light guidance and its interactions with surrounding matter is the main requirement for a detailed study of polymer-optical fibres (POFs). This chapter briefly summarises the physical fundamentals of light and the application of physical laws in optical fibres. Beginning with Maxwell equations and a definition of electromagnetic (EM) waves, interactions in solid matter in the form of polarisation and magnetisation will be discussed. The EM wave equations in vacuum and solid-state media are motivated as fundamental physical law of light's propagation. Scattering phenomena like Mie and Rayleigh scattering occurring in optical fibres are discussed afterward, and their influence onto the fibres' performances is deduced. As it is essential for data transport and signal transmission in optical fibres, boundary phenomena in the form of Snell's law and total reflexions are described by using mathematical and geometrical approaches. Finally, an overview of anisotropic effects like birefringence and the dispersion of light in real media is given in order to finalise the understanding of physical processes in POFs. A summary of the importance of physical effects in optical fibres is made which enables a qualitative understanding of the parameters which determine the efficiency of optical fibres and the currently existing bottlenecks and challenges towards high-performance polymer-optical fibres.