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Passive Q switching of Er:glass (1.53 microm) with a new, robust, solid-state saturable absorber, Co(2+):Y(3)Sc(2)Ga(3)O(12), has been demonstrated. Q-switched pulses of 20 ns and 4 mJ of energy were obtained. An absorption cross section of 5 x 10(-20) cm(2) was measured. Preliminary results for a Co(2+):Y(3)Al(5)O(12) saturable absorber Q switch are also discussed.

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Spectroscopic and laser properties of three different Er3+−doped garnet systems are characterized by employing the Judd–Ofelt (JO) analysis. The three garnet hosts are Y3Al5O12 (YAG), Y3Sc2Ga3O12 (YSGG), and Gd3Ga5O12 (GGG). The JO model has been applied to the room temperature absorption intensities of Er3+ (4f11) transitions to establish the so-called JO intensity parameters: Ω2, Ω4, and Ω6 in the three garnet hosts. The intensity parameters are used to determine the radiative decay rates (emission probabilities of transitions) and branching ratios of the Er3+ transitions from the excited state J manifolds to the lower-lying J′ manifolds. The predicted decay rates and branching ratios of these Er3+ transitions in YAG, YSGG, and GGG hosts are compared. From the radiative decay rates, the radiative lifetimes of the Er3+ excited states are determined in the three garnets and are also compared. We also report the spectroscopic quality factors, Ω4/Ω6, obtained for the three garnets. The quantum efficiencies of the I413/2→I415/2 Er3+ transition in YAG, YSGG, and GGG are determined to be ∼79%, 82%, and 85%, respectively.

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