Laser emission with low quantum defect in Yb: CaGdAlO4

It is demonstrated that 2% Yb: CaGdAlO4 (called CAlGO) presents favorable thermomechanical properties with a high measured thermal conductivity (Kc = 6.3 and Kc = 6.9 W m(-1) K(-1). A laser oscillation in this material at 1016 nm is demonstrated for the first time to our knowledge while pumping at 979 nm. This implies a very small quantum defect (3.5%). A simple new figure of merit that takes into account thermomechanical properties and quantum defects is proposed here to compare the resistance of materials under high-power laser pumping. Consequently, Yb:CAlGO is similar to garnets and sesquioxides in regard to laser power resistance.