1 123 nm passively Q-switched Nd: YAG laser based on gold nanocages and MoS₂ saturable absorbers

Gold nanocages (GNCs) were successfully prepared by seed-mediated method and its nonlinear saturated absorption characteristic at 1123 nm was verified for the first time. As a comparison, a MoS₂ saturated absorber was prepared. Based on GNCs and MoS₂ as saturable absorber (SA), respectively, passively Q-switched Nd: YAG lasers at 1 123 nm were demonstrated.When Q-switched laser with MoS₂ as SA, Q-switched pulse with the shortest pulse duration of 412 ns and maximum pulse repetition rate of 233 kHz was achieved under the pump power of 6.81 W with the maximum average output power of 208 mW. When Q-switched laser with GNCs as SA, Q-switched pulse with the shortest pulse duration of 253 ns and maximum pulse repetition rate of 326 kHz was achieved under the pump power of 6.04 W with the maximum average output power of 221 mW. Compared with the experimental results of MoS₂ Q-switched laser, the gold nanocage Q-switched laser has higher output power and efficiency, narrower pulse width and higher repetition rate. These results indicate a great potential of the GNCs film as SA in the near-infrared region.