Novel Non-Stoichiometric Co~(2+):Spinel Passive Q-Switch

摘要

The development of an alumina-rich cobalt-doped spinel saturable absorber for the passive q-switching of1530-1555 nm lasing is reported1. This optimized composition results in crystals with excellent dopant uniformity thatare highly manufacturable. The crystal growth and materials characterization are described as well as initial passive qswitchtesting of the material. The single crystals grown and investigated crystallized in the Fd3m space group andhave the formula Mg1-xCoxAlyOz where x is greater than 0 and less than 1, y is greater than 2 and less than about 8, andz is between about 4 and 13. Comparison data of stoichiometric spinel MgAl2O4 and alumina-rich non-stoichiometricspinel MgAl6O10 are presented. The spinel lattice is comprised of octahedral and tetrahedral cationic sites, and in thealumina-rich spinel essentially all of the magnesium and cobalt occupy tetrahedral sites. The alumina-rich cobalt-dopedspinel studied exhibited uniform cobalt-dopant distribution throughout the crystal and desirable mechanical and physicalproperties. Q-switched pulses were produced using the alumina-rich Co~(2+):MgAl6O10 saturable absorber in a 980 nmdiode-pumped Yb:Er:glass solid-state-laser operating at 1543 nm. The q-switching established employed the 4T1absorption band of the Co~(2+): MgAl6O10 and with quasi-CW pumping, pulsewidths greater than 20 ns, pulse energies ofgreater than 250 μJ, and free-running pulse repetition frequencies (PRFs) up to 1.2 kHz were demonstrated.