Optical and laser properties of Yb<sup>3+</sup>-doped Al<sub>2</sub>O<sub>3</sub>–P<sub>2</sub>O<sub>5</sub>–SiO<sub>2</sub>large-mode-area photonic crystal fiber prepared by the sol–gel methodShikai Wang, Lili Hu, Meng Wang et al.|Laser Physics Letters|2013Cited by 17