Temporal shape of a Q-switched pulse envelope and (b) pulse train of the QML Nd:GYSGG laser. 

Passively Q-switched mode-locked dual-wavelength Nd:GYSGG laser using graphene oxide saturable absorber is demonstrated. The output spectrum peaked at 1057.28 nm and 1060.23 nm with wavelength spacing of 3 nm has been measured. At the pump power of 5 W, the maximum average output power of 0.189 W was obtained with the optical conversion efficiency of 3.79%. The mode-locked pulse inside the Q-switched envelope has a repetition rate of 100 MHz and its pulse width is estimated to be about 441 ps. In addition, a simple way to fabricate few layers graphene oxide saturable absorbers has been reported. 

Optics Communications , 2015