Optical fibres now constitute the backbone of the world’s long-distance telecommunications systems and are also being used increasingly in other areas, such as sensing, biophotonics, automotive, etc. The course sets out to provide a basic understanding of optical transmission systems concentrating on light propagation along fibres and light processing using fibre- and planar waveguide-based devises. Light propagation includes: modal propagation and Maxwell's equations; ray tracing, Snell's and Fesnel's Laws; single-mode, multi-mode and special fibres; pulse propagation and dispersions; nonlinear effects; fibre and planar waveguide fabrication; analytical and numerical techniques; birefringence and bend loss. Light processing devices include: couplers and splitters; gratings and arrayed waveguide gratings; Mach-Zehnder and multimode interferometers; optical amplifiers and attenuators; polarisers.  With knowledge of the basic physical principles of these key photonic components we consider how they affect the practical performance and limits; and how they influence the design of real-world telecommunication systems.  Laboratory work covers mainly hands-on fibre-based experiments and some numerical simulations.