Thermal effect of Nd:YAG bonded on diamond by Mo/Au metal intermediate layer at room temperature

To overcome the thermal effect of a Nd:yttrium aluminum garnet (YAG) disk, a polycrystalline diamond substrate is successfully bonded to the Nd:YAG disk using a Mo/Au interlayer at room temperature. The results show that the Nd:YAG disk and diamond are almost completely bonded, with some voids at the edge of the bonding layer. Scanning electron microscopy analysis shows that the bonding interface with a thickness of 143 nm is continuous and free of nanodefects. In addition, a numerical model is developed to analyze the thermodynamic properties of the Nd:YAG/diamond composite structure. The analytical results show that a diamond heat sink significantly reduces thermal aberration compared with Cu and SiC heat sinks. Furthermore, the bending optical path difference (OPD) is proved to be a major component of the total OPD. This study is expected to help realize diamond-based laser systems with high-power output.