Nd-doped phosphate glasses for high-energy/high-peak-power lasers

The composition and properties of neodymium-doped (Nd-doped) phosphate glasses used for simultaneous high-energy (103–106 J) and high-peak-power (1012–1015 W) laser applications such as fusion energy research, are reviewed. The most common base glasses are meta-phosphates (O/P ∼3) with the approximate composition: 60P2O5–10Al2O3–30M2O/MO; K/Ba or K/Mg are typical modifiers. The spectroscopy of Nd3+ in these glasses is well understood and laser properties can be accurately determined from measured spectroscopic properties. The major mechanisms for Nd3+ non-radiative relaxation are reviewed and empirical expressions are presented that predict these effects in phosphate glasses. Optical and thermal–mechanical properties have been measured on a number of laser glasses and can be correlated with composition. Sub-critical crack growth rates in stress regions I, II and III have been reported for the first time in phosphate laser glasses. The mechanism for Pt inclusion formation and dissolution has been studied leading to damage resistant (Pt-inclusion-free) laser glasses.