Versatile mode-locked patterns in a fiber laser using silica-coated gold nanorods as saturable absorber

We demonstrate the generation of versatile mode-locked patterns in fiber laser with the saturable absorber (SA) based on gold nanorods (GNRs). The GNRs were synthesized by the seed-mediated growth method, and then were encased with silica in order to improve their photo-thermal stability. The silica-encased GNRs (GNRs@SiO2) SA presents a modulation depth of 3.9% and nonsaturable loss of 29.7% through a balanced twin detector measurement technique. Using the SA with high nonlinearity and excellent saturable absorption in the fiber laser cavity, versatile mode-locked patterns such as fundamental mode-locked soliton, harmonic soliton, dual-wavelength bound soliton, and soliton bundle can be achieved. The experimental results indicate that the GNRs@SiO2 could be a promising nonlinear optical material for potential applications in the field of ultrafast photonics.