This book presents current research in the study of lasers. Topics discussed include recent progress of high peak power solid state lasers; laser annealing of composite materials with metal nanoparticles; optical properties of rare earth ions induced by femtosecond laser; high intensity laser-matter interactions; low-dimensional models for characterising mode-locked fibre lasers; single-frequency fibre laser; ZnO nanostructures deposited by laser ablation; diode laser forming of steel parts and laser cladding.