“…1,2 Gain switching of a Cr 4ϩ :YAG laser pumped with a Q-switched Nd:YAG microchip laser was demonstrated recently. 3 A more direct, simple, and efficient approach is passive Q switching of a 1.5-m laser with an absorber crystal (e.g., Co 2ϩ :LaMgAl 11 O 19 , 4,5 Er:Ca 5 (PO 4 ) 3 F, 6 U 4ϩ :CaF 2 , 7,8 U 4ϩ :SrF 2 , 9 Co 2ϩ :ZnSe, 10 Cr 2ϩ :ZnSe 11 ) or with a semiconductor saturable absorber mirror (SESAM). 12 Laser emission at ϳ1.5 m has been reported from several gain materials including Cr 4ϩ :YAG (review on Cr 4ϩ -doped garnets), 13 Yb 3ϩ :Tm 3ϩ :YLiF 4 , 14 Er:Ti:LiNbO 3 , 15 and, most commonly used for diodepumped bulk lasers, Er:Yb:glass.…”