This textbook, now in the second edition, offers a completely up-to-date and in-depth introduction to the principles and applications of optoelectronic devices and systems. The text gives a detailed description of optical fibre waveguides, optical fibre cables and their characteristics, manufacturing process and drawing of optical fibres. In addition, it deals with photon sources, photon detectors, fibre optics as a medium and LAN and WAN systems, short and long haul optical fibre communication systems, electro-optic modulators and their characteristics. The second edition possesses a new section on Optical Fibre Based Broadband High Speed Network in Chapter 8, thus highlighting an updated version. Apart from this, a new chapter on Intensity Dependent Refractive Index Effect has been introduced into the text that discusses the effect of focusing on spatial and temperature profiles in a non-linear crystal medium. This chapter further explains the various physical phenomena like the creation of sharp opaque filaments, irradiation induced damaging of the crystal, oscillatory waveguide propagation, saturation effects and other properties in detail.