The study of fibre lasers is an advanced field of modern science entering all branches of science. This field continues to vastly expend with state-of-the-art developments across the entire spectrum of scientific, military, medical, industrial and commercial applications ranging from spectroscopy to material cutting, welding and marking. This book is a self-contained collection of scholarly papers targeting an audience of practicing researchers, academics, Ph.D. students and other scientists. This book describes advanced research and applications of the rapidly developing field of fibre laser technology filling the very important role of providing students, researchers, and technology managers with valuable, timely, and unbiased information on the subject. The objective of this book is to highlight recent progress and trends in fibre laser technology. The authors hope that this book will be useful for students, researchers, and professionals who are working in the area of fibre lasers. This book will serve also as an interesting and valuable reference that will impact, stimulate and promote further advances in the area of fiber lasers. In summary, the book discusses some of the most important topics that have made a tremendous impact in the growth of science and technology today.