Co2+: MgAl2O4 A New Material For Saturable Absorber Passive Q-switch

High absorption cross section of 3.5 x 10-19 cm2 permits Q-switching of Er:glass laser without intracavity focusing both with flash lamp and diode-laser pumping. Negligible excited-state absorption results in high contrast of Q-switch, i.e. the ratio of initial (small signal) to saturated absorption is higher than 10. Finally, excellent optical, mechanical, and thermal properties of the crystal give an opportunity to design compact and reliable laser sources with this passive Q-switch.
The size of the device is decreased and a high voltage power source is removed when passive Q-switches or saturable absorbers are used to create high power laser pulses instead of electro-optic Q-switches. The strong, sturdy crystal known as spinel polishes nicely. Without extra charge compensation ions, cobalt may easily replace magnesium in the spinel host. For both flash-lamp and diode laser pumping, the Er:glass laser's high absorption cross section (3.510-19 cm2) allows Q-switching without intracavity focusing.
The average output power would be 580 mW with a pulse width as low as 42 ns and an absorbed pump power of 11.7 W. The energy of a single Q-switched pulse was calculated to be roughly 14.5 J, and the peak power was 346 W at a repetition rate of about 40 kHz. Also, several polarization states of the Co2+:LMA's passive Q switching action were examined.