Thermal Lensing and Multiwatt Microchip Laser Operation of Yb:YCOB Crystals

Identifier:  PC:2896

Handle: https://hdl.handle.net/20.500.11797/PC2896

Authors:  Xavier Mateos; Pavel Loiko; Josep Maria Serres; Haohai Yu; Junhai Liu; Konstantin Yumashev; Uwe Griebner; Valentin Petrov; Magdalena Aguiló; Francesc Díaz

Abstract:
Thermal lensing is studied in monoclinic Yb:Ca4YO(BO3)3 (Yb: YCOB) oxoborate crystals cut along the optical indicatrix axes. For all orientations, the thermal lens is positive. In the Z-cut crystal, the sensitivity factors of the thermal lens are MZX ¼ 2:4 and MZY ¼ 2:8 m1=W (for EkX), and the astigmatism degree is as low as S=M ¼ 14%.The positive thermal lens in Yb:YCOB is related to the large thermal expansion and strong photoelastic effect. Microchip lasers are realized with 3-mm-long X, Y, and Z-cut 15 at.% Yb:YCOB crystals. With a Z-cut crystal, maximum output power of 8.35 W is achieved at ¿1040 nm with slope efficiency of 70%. Using various crystal cuts and output coupler transmissions, multiwatt emission in the spectral range of 1033¿1091 nm is demonstrated.