Room-temperature bonding with post-heat treatment for composite Yb:YAG ceramic lasers

There are many advantages of composite transparent ceramic materials in laser applications; hence, methods to improve bonding toughness are of great interest for scientific and industrial applications of high average-power lasers. We used a combination of room- temperature bonding (RTB), involving a fast-atom beam surface treatment and diffusion bonding via post-heating, to fabricate laser materials suitable for a variety of oscillators/amplifiers. Yb:YAG/YAG composite ceramics and Yb:YAG/sapphire hetero composites were fabricated by RTB. The continuous wave laser oscillation performance with a Yb:YAG/sapphire composite disk was superior to that without a sapphire heat-conducting layer. The post-heated Yb:YAG/YAG composite ceramics exhibited a bending strength of 470 MPa which was 8.9 times as high as that of similar composite ceramics fabricated by usual diffusion bonding. We optimized the post-heating conditions of the Yb:YAG/sapphire hetero composite, including the maximum temperature and heating time course to avoid crack generation.