Fabrication and laser behaviors of Yb3+ doped silica large mode area photonic crystal fiber prepared by sol–gel method

•LMA PCF was prepared by sol–gel method and stack-capillary-draw technique.•The spectra properties of Yb3+, Al3+ co-doped silica glass were discussed.•The laser experiment and laser behaviors were illustrated. Yb3+, Al3+ co-doped silica large mode area photonic crystal fiber (LMA PCF) has been prepared by sol–gel method combined with stack-capillary-draw technique. The core glass with composition of 0.3Yb2O3–3Al2O3–96.7SiO2 (mol%) has 927μs fluorescence lifetime, 0.82pm2 stimulated emission cross section at ∼1μm and 1.4ppm residual hydroxyl group. 6.8W continuous-wave fiber laser ranging from 1040 to 1070nm has been obtained from a piece of 98-cm-long PCF with the Yb3+ concentration of 6.49×1019ions/cm3 pumped by a commercial 927-nm laser diode. The laser has a threshold of 1.45W launched power with a slope efficiency of 48%. The maximum output power of 6.8W is limited by the available pumping power, and the optical loss is 1.2dB/m at 1053nm. To the best of our knowledge, this is the highest laser output power report on Yb3+, Al3+ co-doped silica LMA PCF prepared by sol–gel method.