Ultrafast photonics has become an interdisciplinary topic of high international research interest because of the spectacular development of compact and efficient lasers producing optical pulses with durations in the femtosecond time domain. Present day long-haul telecommunications systems are almost entirely based on the transmission of short bursts or pulses of laser light along silicon optical fibres, with Erbium-doped fibre amplifiers inserted to regenerate the signals periodically. The phenomenal success of optical fibre communications has created a substantial opto-electronics industry that provides efficient laser sources, high-speed modulators, optical amplifiers and detectors.Although optical data transmission is now well established, current systems approaches will eventually cease to meet the ever-increasing demands of data-communication. Existing wavelength division multiplexing (WDM) schemes will need to be complemented with time-domain multiplexing (TDM) techniques involving digital optical signals using ultrashort laser pulses.This book brings together contributions from world experts at major collaborative research initiatives throughout Europe, the USA and Japan and considers all aspects of this very active area of research. Topics covered range from the fundamental physics of optical interactions and material properties through to new system concepts for ultrahigh-capacity data transfer and processing using femtosecond pulses. Areas of specific scientific breakthrough and subsequent technological advance have been emphasised.Each chapter of the book presents a tutorial style introduction to the topic, suitable for postgraduate students and others with a basic knowledge of photonics, and will be a valuable reference for existing researchers in the field.