Upconversion and reduced 4F3/2 upper-state lifetimes in intensely pumped Nd:YLF

Summary form only given. Intense diode-pumping of Nd-doped active elements in Q-switched lasers is a common approach to improve system efficiency, reliability, and reducing size. Compact laser devices using highly doped active elements with short pump absorption depths are particularly attractive for high average power applications since the thermal loads are more easily dissipated from the small-volume active elements. The ⁴F_3/2 upper-state lifetime, τ, is an important parameter for engineering such lasers since it affects the achievable stored-energy density for a given pumping scheme and ultimately determines the output energy of the system. Energy transfer upconversion (ETU) and sequential two-photon excitation processes (STEP) have been identified as important upconversion mechanisms. The same upconversion processes observed to reduce 1 μm upper laser lifetime in Nd:YLF may also offer the potential for diode-pumped visible and near-UV laser sources in this material