Accurate method for the measurement of absorption cross sections of solid-state saturable absorbers

A rigorous approach taking into account both the temporal and spatial distributions of the pulsed probe beam used for transmission measurements of solid-state saturable absorbers is applied to characterise these absorbers accurately. The use of this method can significantly influence the resulting value for the ground-state absorption cross section. It also permits us to avoid the introduction of an artificial excited-state absorption in systems where, according to energy-level diagrams. no such loss should occur. This is illustrated in the case of passive Q-switchers for 1.5-mum lasers such as Co2+-doped LaMgAl11O19 and MgAl2O4 and Co2+- or Cr2+-doped ZnSe and ZnS.