Nanocomposites with gold nanorod/silica core-shell structure as saturable absorber for femtosecond pulse generation in a fiber laser.

Ultrafast fiber lasers play a significant role in our society with many aspects ranging from fundamental physics to industrial purposes. Searching for high-performance saturable absorbers (SAs) is vital to the developments of ultrafast fiber lasers. Gold nanorods (GNRs) have been discovered to possess saturable absorption effect. However, a major obstacle to make the GNRs as high-performance and practical SA is the low optical damage threshold. To overcome this drawback, herein we proposed the nanocomposites with gold nanorods/silica core-shell structure (GNRs@SiO(2)) as a high-performance SA for ultrashort pulse generation in a fiber laser. The GNRs@SiO(2) SA presents a modulation depth of 4.2% and nonsaturable loss of 45.6%. With the proposed GNRs@SiO(2) SA, 379 fs pulse was directly obtained from the fiber laser. The achieved results demonstrated that the GNR@SiO(2) could be indeed a good candidate of high-performance SA towards practical applications in the field of ultrafast photonics.