The present book has been written to meet the requirements of students and is based on lectures given by the Author, at the University of Lucknow, Lucknow. The book provides very systematic, clear and in logical sequence, description of various topics, in a very lucid and simple style, specially its mathematical approach and its interpretation. Starting with the fundamental of fiber-optics, the chief characteristics of various topics have been explained in 10 chapters. To reinforce, numerical example have been also given. Thus the book serves as a reference book to all under graduate as well as post-graduate students and also teachers. Thus the book is fully compact and complete in itself.