Influence of nonradiative relaxation of the levels of an active transition of Nd$^{3+}$ ions in glass on the amplification of high-power nanosecond pulses

It is shown that fast thermalization, characterized by a time constant $\tau_T\lesssim1$ psec, of the Stark components of the levels of the active transition giving rise to the 1.06 $\mu$ emission from Nd$^{3+}$ ions in glass is responsible for the high efficiency of amplification of 1–100 nsec pulses in high-power neodymium laser systems.