Graphene Q-Switched Cr:ZnSe Laser

Abstract

For the first time, to the best of our knowledge, a stable Q-switched Cr:ZnSe laser was realized with the graphene saturable absorber grown on SiC substrate. Under an absorbed pump power of 1.8 W, a maximum average output power of 256 mW was obtained with an optical-to-optical conversion efficiency of 14% and a slope efficiency of 19.6%, corresponding to the highest single pulse energy of 1.66 $\mu \text{J}$ . The shortest pulse width and highest pulse repetition rate were 157 ns and 169 kHz, respectively. Using a nanoscan beam analyzer, the $M^{2}$ values of graphene Q-switched Cr:ZnSe laser were measured to be 1.09 and 1.16 for the horizontal and vertical directions. The experimental results indicate that graphene, combined with SiC substrate, provides a simple and cheap way to achieve efficient passively Q-switched lasers at 2.4 $\mu \text{m}$ .