Optical Fiber Sheath: Advantages and Principles

This lecture covers the advantages of coating optical fibers with a sheath of slightly lower refractive index, such as protection from damage and prevention of adjacent fibers touching. It also explains the principles behind Huygens' principle, total internal reflection, and Fermat's principle on wave propagation. The lecture delves into topics like the propagation of waves in different media, laws of reflection and refraction, and the concept of optical path. Additionally, it discusses the importance of the Huygens principle in understanding diffraction and interference, as well as the behavior of light rays in conductive and non-conductive environments.