Fabrication and Laser Amplification Behavior of Yb3+/Al3+ Co-Doped Photonic Crystal Fiber
Yb<sup>3+</sup>/Al<sup>3+</sup> co-doped silica glass with the composition of 0.1Yb<sub>2</sub>O<sub>3</sub>-1Al<sub>2</sub>O<sub>3</sub>-98.9SiO<sub>2</sub> was prepared by sol-gel method combined with high-temperature sintering. Using this glass as active core, a photonic crystal fiber (PCF) with 105-μm core was fabricated by the stack-capillary-draw technology. The refractive index fluctuation of this core rod is as low as 2 × 10-4, implying that highly homogenous silica preform can be realized in this method. Furthermore, this PCF achieved a maximum amplified power of 255 W, with a slope efficiency of 65.7%. It indicates that Yb<sup>3+</sup>-doped silica preform prepared by the sol-gel method can be employed in the field of high-power laser.