This is the Second Edition of the widely acclaimed book on Optimal Communications - a well-balanced combination of optoelectronics and communication theory which will complement existing, more introductory texts in this field. The book is self-contained and deals with the fundamental operation of the main components, together with their limitations in the context of different system requirements. Material has been updated to emphasise single-mode fibres and the new technological developments, and new material added where necessary, such as inelastic scattering, non-linear propagation, optical amplifiers and coherent systems. Semiconductor theory is developed in the context of optoelectronic components. Review from the First Edition: "This book can be confidently recommended both as an undergraduate text and as an introduction for the newcomer to optical communications" qit-Electronics & Power-qit