Efficient bleachable filter based on Co{sup 2+}:MgAl{sub 2}O{sub 4} crystals for Q-switching of {lambda} = 1.54 {mu}m erbium glass lasers

It is suggested that Co{sup 2+}:MgAl{sub 2}O{sub 4} spinel crystals can be used as efficient passive Q-switches for {lambda} = 1.54 {mu}m erbium lasers. A laser with an active element 3 mm in diameter and 55 mm long, containing such a switch, generated pulses with the structure of the TEM{sub 00} mode, of 5.7 mJ energy, and of 50 ns duration. The energy was only 20% less than that attained by active switching with a device based on frustrated total internal reflection. (letters to the editor)