This book provides a microwave importance of preparation of glasses and applications of phosphate glasses. Importance of TMO to probe local structure and electron paramagnetic Resonance detailed studies on 5 4+ ions into the glasses have been presented. Optical absorption and Photoluminescence studies of TMO is discussed in detail and correlated to EPR studies. Important structural parameters such as Spin-Hamiltonian parameters and Optical parameters have been estimated and presented.