It is a matter of pleasure to present the Luminescence studies on Sm3+, Eu3+, Dy3+, Er3+ and Er3+/Yb3+ ions in potassium niobate silicate glasses. The prime objectives of this book are: To prepare Potassium Niobate Silicate (K- Nb- Si) glasses doped Sm3+, Eu3+, Dy3+, Er3+ and Er3+/Yb3+ ions To characterize and optimize the prepared glasses by the conventional spectroscopic techniques like absorption, emission, decay, etc. measurements. To identify the optimum concentrations of dopant ions for efficient luminescence. To find lifetime of the emission level of rare earth ion by increasing active ion concentration This book has been written in a simple and lucid manner. Every effort has been made to make the treatment simple and comprehensive. The topics are explained with the help of clear diagrams, S.I. units are used throughout the book.In spite of our best efforts, some errors might have crept. The authors do not take any legal responsibility for such errors and omissions.If they are brought to our notice, they will be corrected in next edition. Hope this book will be found useful be the research students"