Both reduced graphene oxide (RGO) and gold (Au) nanoparticles have shown distinct nonlinear optical characteristics, such as saturable absorption, that are appropriate for generating ultrashort pulse lasers. Unfortunately, there are no studies of Q-switched waveguide lasers using RGO and RGO modified with Au nanoparticles (Au-RGO) as saturable absorbers. Here we perform the pump-probe experiments to investigate the nonlinear optical absorption properties of RGO and Au-RGO. Our results show that, compared with RGO, Au-RGO has advantages of a higher modulation depth, faster optical response and wavelength-independent nonlinear absorption, which demonstrates that nonlinear optical properties of Au-RGO have been enhanced owing to the Au nanoparticles. Moreover, the laser emission of Q-switched Nd:YAG channel waveguidewith Au-RGO as a saturable absorber has been obtained. In comparison with the waveguide laser system utilizing RGO, the Q-switched laser observed with Au-RGO exhibits a shorter pulse duration and a higher repetition frequency, indicating the potential application of Au-RGO as a cost-effective saturable absorber in the pulsed waveguide laser systems.

中文翻译：

---

通过 Au 修饰增强 RGO 的非线性光学特性：Q 开关波导激光器的应用

还原氧化石墨烯 (RGO) 和金 (Au) 纳米粒子都显示出独特的非线性光学特性，例如可饱和吸收，适用于产生超短脉冲激光。不幸的是，没有关于使用 RGO 和用 Au 纳米粒子 (Au-RGO) 改性的 RGO 作为可饱和吸收体的 Q 开关波导激光器的研究。在这里，我们进行泵浦探针实验来研究 RGO 和 Au-RGO 的非线性光学吸收特性。我们的结果表明，与 RGO 相比，Au-RGO 具有更高的调制深度、更快的光学响应和与波长无关的非线性吸收等优点，这表明 Au-RGO 的非线性光学特性由于 Au 纳米颗粒而得到增强。此外，调Q Nd的激光发射：获得了以Au-RGO为可饱和吸收体的YAG通道波导。与使用 RGO 的波导激光系统相比，使用 Au-RGO 观察到的 Q 开关激光具有更短的脉冲持续时间和更高的重复频率，表明 Au-RGO 作为具有成本效益的可饱和吸收体在脉冲波导中的潜在应用激光系统。