A novel approach and segregation behavior of heavily doped Nd:YAG/YAG composite structure by solid-state crystal growth

As a prospective alternative technique for single crystal growth, solid-state crystal growth (SSCG) is applied in the fabrication of a Nd:YAG/YAG composite structure with a high Nd3+ doping concentration. The microstructure morphologies and segregation behavior in the ceramic matrix, growth interface, and grown crystal are investigated. The results indicate that the dopant ions diffuse along with the grain boundary migration during the SSCG process while the segregation coefficient at the growth interface is higher than that of the grain boundary. A homogeneous grown crystal without segregation generates in a 6 at.% doping sample. When the doping concentration exceeds the solubility limit of the crystal lattice, surface morphology defects emerge as numerous protuberances in an 8 at.% doping sample. The SSCG technique has bright application prospects in heavily doped YAG crystal, especially for active ion diffusion limitation during the fabrication of planar waveguides.