Modeling of the Co2+ saturable absorber Q-switch for the Er:Yb:glass laser (1.534 μm)

We have modeled the passive Q-switch performance of divalent cobalt (Co2+) and its spectroscopic parameters in various host media for the Er:Yb:Glass laser that operates near 1.534 mu m. Our method involves the use of rate equations that assume a three-level gain medium and a four-level absorber medium including excited-state absorption (ESA). Numerical integration techniques are used where analytical functions are unobtainable to describe the dynamics within the systems that we have examined. Input into the rate equations is obtained from experimental data that include Co2+ ion concentrations, cross-sections, and lifetimes obtained by time-resolved spectroscopy. The calculated laser output in terms or pulse energies (mJ) and pulsewidths (FWHM) in ns is compared with experimental results based on different Co2+ absorber host matricies and different cavity designs.