Lead sulfide nanoparticles for dual-wavelength ultrashort pulse generation

Nanoparticle materials have many potential applications in the area of electronics and optoelectronics due to their unique and versatile properties. In particular, lead sulfide nanoparticles (PbS NPs) have shown excellent ultrafast photonics and can be applied to communication systems because of their low bandgap, high thermal damage threshold and stability. The wavelength division multiplexor (WDM) technique is vital to fiber optical communication, which allows the transmission of many different-wavelength signals in one fiber cable. However, PbS NPs for multi-wavelength pulse generation has not been reported until now. In this work, PbS NPs have been investigated and successfully applied in an Er-doped fiber laser as a saturable absorber (SA) to generate a dual-wavelength short pulse for the first time. A picosecond-level ultrashort pulse at center wavelengths of 1545 and 1585 nm can be achieved simultaneously or respectively. It is worth mentioning that the two wavelengths are separated up to 40 nm, which can significantly expand the optical communication capacity. The result suggests that PbS NPs as smart nonlinear optical components have wide applications in optical communications, short-pulse lasers, and even high-performance photodectors.