Cr3+ doped Gd(Sc,Ga) garnet (GSGG) was the first tunable cw laser of a transition metal ion at room temperature.1 Other Cr3+:Ga garnets and Cr3+: Gd(Sc,Al) garnets2 exhibit similar laser characteristics. All these crystals have similar spectroscopic properties showing strong broadband luminescence in the 700-950-nm region with lifetimes and emission cross sections of the order of 100-200 µsec and 1×10−20 cm2, respectively. R-line emission (2E→4A2) is negligible. The vibrationally broadened 4T2→4A2 transition is observed, resulting in a four-level laser. Therefore, analysis of the Cr3+:GSGG laser is representative of this whole class of new laser.
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