Plasmonic photo-bleaching enabled broadband nonlinear optics and ultrafast photonics

Gold‑titanium nitride (Au/TiN), a prominent plasmonic transition metal nitride, exhibits superior advantages in electronic and optical properties, making it adaptable for applications in modern photonics technologies. Herein, novel gold‑titanium nitride (Au/TiN) is a typical representative of the plasmonic photo-bleaching metal nitrides, which comprises modified nanoclusters of gold on TiN for enhancing carrier mobility. These materials can be exploited as an ultrafast optical switch, which shows saturable absorption behavior with strong optical nonlinearity. The chemical composition and morphology of as-prepared plasmonic Au/TiN materials are systematically characterized. The plasmonic photo-bleaching material is directly transferring to a piece of tapered fiber (TF) to fabricate the Au/TiN-based broadband nonlinear saturable absorber (SA). Nonlinear optical (NLO) properties of the Au/TiN plasmonic nanomaterial are measured from the 1.06 to 2.0 μm wavelength regions for the first time to the best of our knowledge. Additionally, stable passively mode-locked lasers based on the Au/TiN-SA devices are realized with the shortest pulse durations of 250 ps, 1.416 ps, and 0.810 ps at 1.0, 1.5, and 2.0 μm bands, respectively. These experimental results indicate that the Au/TiN-SA is an effective broadband nonlinear photonic device in an all-fiber ultrafast laser and can also provide new insights into the design of NLO devices for optoelectronics applications.