Broadband Nonlinear Photoresponse of 2D TiS2 for Ultrashort Pulse Generation and All‐Optical Thresholding Devices

2D titanium disulfide (TiS2) is recently found to have strong light absorption properties from visible to infrared (IR) region. This feature is highly attractive for applications in nonlinear photonics; however, the mechanism of broadband light–matter interaction is yet to be determined and nonlinear photonic devices are not developed. Here, for the first time, the experimental evidence supporting the mechanism of the broadband nonlinear photoresponse in ultrathin TiS2 nanosheets ranging from 400 nm to 1390 nm is reported through laser Z‐scan measurements. High‐performance nonlinear photonic devices operating in the telecommunication band are also demonstrated. A novel saturable absorber (SA) device is successfully fabricated based on a 2D TiS2‐decorated fiber, which exhibits outstanding ultrashort pulse generation performance with pulse duration of ≈1.04 ps centered at 1569.5 nm. Furthermore, as a stable all‐optical thresholding component, the device can effectively attenuate noise and boost the signal‐to‐noise ratio of the pulse from 1.90 to 10.68 dB. The findings indicate that TiS2‐based SA devices can be developed into excellent highly nonlinear photonic devices, which may advance the development of TiS2‐based optical communication technologies in the future. Ultrathin and uniform semimetallic titanium disulfide nanosheets are synthesized via a colloidal chemistry method. A Z‐scan system is used to confirm their broadband nonlinear optical response from visible to mid‐infrared wavelengths. Thus, TiS2 nanosheet‐based optical devices exhibit excellent performance in mode‐locked fiber lasers and all‐optical thresholding components.