Abstract: A laser uses a rare-earth doped phosphate laser glass characterized by a particularly high rare-earth content to generate the highest possible output power/energy pulses. The laser glass is composed primarily of P2O5, Al2O3, and alkaline earth and alkali earth oxides, and possesses other properties such as physical and thermal properties that are compatible with melting and manufacturing methods. The laser glass can be used in high power and high energy laser systems where laser action is achieved in rod or slab shaped components as well as in waveguide or thin film structures prepared by structuring technologies such as sputtering, ion exchange, and/or direct writing with a femtosecond laser.