Mechanical, thermal and laser properties of Yb:(Sr1−xCax)3Y(BO3)3 (Yb:CaBOYS) for 1 μm laser applications

Yb:Sr3Y(BO3)3 also known as Yb:BOYS has recently demonstrated very attractive laser properties, but a drawback with this material is its brittleness. It could break into small pieces, even under weak thermal loading. This behavior is attributed to its very large thermal expansion anisotropy: <f>αc/αa∼4</f>. This ratio can be lowered to ∼1.7 by replacing 50% of Sr2+ by Ca2+ in the structure, which strengthen the crystal lattice and allows to reduce the brittleness. However, the thermal properties are affected by the Sr/Ca substitution as the thermal conductivity decreases by around 20 at.% for a 30 at.% calcium containing material. Laser characteristics under diode pumping with Yb3+:(Sr0.7Ca0.3)3Y(BO3)3 crystals (containing 15% Yb) remain comparable to those obtained with Yb:BOYS. [Copyright &y& Elsevier]