Polarized spectroscopy and diode-pumped laser operation of disordered Yb:Ca3Gd2(BO3)4 crystal

Identifier:  imarina:9244552

Handle: https://hdl.handle.net/20.500.11797/imarina9244552

Authors:  Pan, Zhongben; Lin, Zhang-Lang; Loiko, Pavel; Zhang, Ge; Zeng, Huang-Jun; Xue, Wen-Ze; Camy, Patrice; Petrov, Valentin; Slimi, Sami; Mateos, Xavier; Diaz, Francesc; Lin, Haifeng; Wang, Li; Chen, Weidong

Abstract:
We report on the growth, structure, polarized spectroscopy and efficient continuous-wave laser operation of an Yb3+-doped disordered calcium gadolinium borate crystal, Yb3+: Ca3Gd2(BO3)4 (Yb:GdCB). Yb:GdCB belongs to the orthorhombic class [sp. gr. Pnma, lattice parameters a= 7.1937(0) Å, b= 15.5311(3) Å, c= 8.6140(7) Å]. The structure disorder of this material originates from a random distribution of Ca2+ and Gd3+|Yb3+ cations over three non-equivalent lattice sites. This leads to broad and smooth (“glassy-like”) absorption and emission spectra at room and low temperatures. The stimulated-emission cross-section of Yb3+, σSE is 0.42×10-20 cm2 at 1025.1 nm for light polarization E || c and the luminescence lifetime of the 2F5/2 state is 644 µs. Continuous-wave laser performance of the Yb:GdCB crystal was evaluated under high-power diode-pumping at 976 nm for three crystal orientations along the crystallographic axes. For an a-cut crystal, a maximum output power of 5.58 W was achieved at ∼1057 nm with a slope efficiency of 51.7% and a linear laser polarization (E || c). The demonstrated power scaling capabilities and broadband emission properties of Yb:GdCB indicate that it is promising for generation of sub-50 fs pulses from passively mode-locked lasers at ∼1 µm.