Solid-state Crystal Growth and Its Application to Fabricate Planar Waveguides

The effect of different factors, i.e., annealing temperature, grain size, and dopant ion on the solid-state crystal growth (SSCG), was studied in this work. In the SSCG process induced by heat treatment, a single crystal absorbs grains near the bonding interface, forming a robust bond. Using this method, a planar waveguide (PWG) consisting of a core layer of 12at% Yb:YAG polycrystal (100 μm) was fabricated and cladded by two YAG single crystal layers. No Yb³⁺ ion diffusion was observed. The CW laser performance of the Yb:YAG PWG was investigated. A maximum power of 1.14 W with a slope efficiency of 16.09% was obtained in the plano-plano resonator, and a maximum power of 1.83 W with a slope efficiency of 9.59% was obtained in the three-mirror resonator. A tunable laser with a continuous output between 1027.5 nm and 1033.5 nm was realized.