Final Activity Report Summary - FIBERLASER (Development of Femtosecond Fiber Lasers for Next-Generation Accelerators) This project targeted development of highly stable (low-noise) fibre lasers and amplifiers producing extremely short pulses of light (in the picosecond and femtosecond time scale). These laser sources are important for a wide range of scientific and technological applications, including but not limited to accelerator technologies. Additional areas of impact include the closely related field of optical frequency metrology and optical clocks, which provide unparalleled timing and frequency precision; interaction of femtosecond pulses with matter, including femtosecond material processing, tissue processing, femtosecond nanosurgery on individual cells. Throughout this project, significant advances have been made in very low-noise laser development, including the discovery of two new laser types. One laser system has been specifically developed for integration into the Euro-XFEL accelerator facility under construction in Hamburg, Germany, as a European-wide effort. The laser system has been successfully delivered to scientists at DESY, the German National Lab, where Euro-XFEL facility is being constructed. Research that has been supported by this project has also led to the development of advanced fibre lasers, which have been successfully utilised in optical clock work, femtosecond modification of materials and tissue, as well as development of the first fibre laser-based nanosurgery system. Research related to this project has made national headlines most recently in early 2010, following the publication of the article describing the discovery of the soliton-similariton fibre laser in Nature Photonics. In addition to the direct scientific results, the group of Dr Ilday has initiated additional European-wide scientific cooperation with two other accelerator centres: the Italian Ellettra Synchrotron (Trieste, Italy), the CLIC work group at CERN (Geneva, Switzerland).