Cobalt-doped transparent glass ceramic as a saturable absorber Q switch for erbium:glass lasers

A new saturable absorber Q switch for 1.54-mum Er:glass lasers is presented. The saturable absorber is a transparent glass ceramic that contains magnesium-aluminum spinel nanocrystallites doped with tetrahedrally coordinated Co2+ ions. We obtained Q-switched pulses of up to 5.5 mJ in energy and 80 ns in duration at 1.54 mum. The relaxation time of (4)A(2) --> T-4(1)(F-4) transition bleaching was measured to be (450 +/- 150)ns. Ground-state and excited-state absorption cross sections at 1.54-mum wavelength were estimated to be (3.2 +/- 0.4) X 10(-19) cm(2) and (5.0 +/- 0.6) X 10(-10) cm(2), respectively. (C) 2001 Optical Society of America.