High-power ultrafast Nd:YVO4 laser mode-locked by graphene saturable absorber

The large-area monolayer graphene film was grown on Cu foil by chemical vapor deposition (CVD) technique. After transferring it to a quartz substrate, the graphene film was used as a saturable absorber (SA) in an Nd:YVO4 laser. Mode-locked laser pulses of 7.6 ps were obtained at a central wavelength of 1064 nm. Under a pump power of 6.7 W, the average output power reached a high value of 2.5 W, corresponding to an optical-to-optical efficiency of 37.3% and a slope efficiency of 40.3%. The pulse repetition rate was 87.4 MHz and the maximum pulse energy was as high as 28.6 nJ. To date, this might be the highest average output power for mode-locked laser by using graphene SA. Our results illustrate that graphene can potentially be employed in the practical low-cost and high-power mode-locking laser system.