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

Yb:Sr 3 Y(BO 3 ) 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: α c /α a ∼ 4. This ratio can be lowered to ∼1.7 by replacing 50% of Sr 2+ by Ca 2+ 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 Yb 3+ :(Sr 0.7 Ca 0.3 ) 3 Y(BO 3 ) 3 crystals (containing 15% Yb) remain comparable to those obtained with Yb:BOYS.