Influence of Excited-State-Energy Upconversion on Pulse Shape in Quasi-Continuous-Wave Diode-Pumped Er:LiYF $_{4}$ Lasers

In this paper, we demonstrate the temporal dependency of an Er:LiYF
₄
laser on the upper laser level energy transfer upconversion. By spectroscopic measurements and numerical simulations, we calculate a value for this upconversion of 9 × 10
^-17
cm
³
/s. We also report a 60% higher average output power for short-pulse duration, which is complementary to some earlier findings.