Gold nanorods as the saturable absorber for a diode-pumped nanosecond Q-switched 2  μm solid-state laser

Gold nanorods (GNRs) with an average aspect ratio of 15 were experimentally exploited as the 2 μm saturable absorber in a laser diode pumped Tm:YAG laser for the first time, to the best of our knowledge. Q-switched pulses with a maximum average output power of 380 mW, a minimum pulse width of 796 ns, and a pulse repetition rate of 77 kHz were achieved under the LD pump power of 6.2 W. Our results indicate that GNRs with a large aspect ratio are promising saturable absorbers in the 2 μm wavelength region.