Gold Nanorods as Single and Combined Saturable Absorbers for a High-Energy -Switched Nd:YAG Solid-State Laser

Gold nanorods (GNRs) with surface plasmon resonance peak at 1063.8 nm were fabricated and experimentally exploited as the single and combined saturable absorber (SA) in a Q-switched Nd:YAG laser for the first time. In the situation using GNRs as a single SA, the maximum pulse energy of 19 μJ was achieved at a pulse repetition rate of 20 kHz. However, due to the small effective modulation depth of the GNRs, microsecond pulses were generated in such a GNRs-based passively Q-switched laser. A novel configuration using GNRs as a combined SA in an acoustooptic Q-switched Nd: YAG laser was proposed. The small nonlinear loss modulation induced by the GNRs played a distinctive role in flexibly manipulating the nanosecond pulse waveforms. Our study demonstrated the feasibility of generating high-energy pulses by singly using GNRs-based SA in all solid-state lasers. Meanwhile, a new application mode incorporating GNRs as a combined SA was studied, providing an alternative method to take advantage of the nanomaterial-based SA with a relatively small modulation depth.