Cos2 With 3d Valence Electron Shell Structure For Pulsed Laser Application

CoS2 with a three-dimensional porous structure has attracted great interest because of its excellent electrical, magnetic, and optical properties. However, the nonlinear optical properties of CoS2 have not been studied so far. Here, CoS2 is utilized to act as an optical modulator first. A passively mode-locked Er-doped fiber laser is proposed with CoS2 on a microfiber. The nonlinear optical properties of CoS2 are systematically characterized. The modulation depth is 3.7% through a dual-balance monitoring system. More importantly, CoS2 has not been applied in ultrafast photonics. The mode-locked rectangular shape pulses with large chirp based on CoS2 saturable absorber have been achieved for the first time to our knowledge. The rectangular pulsed fiber laser has many advantages, such as high pulse energy and high pumping efficiency. It marks further development of CoS2 materials in optical fiber communication, ultrafast photonics, and other aspects.