Few-layer ZrTe3 nanosheets for ultrashort pulse mode-locked laser in 1.55 μm region

As a new two-dimensional (2D) material, zirconium telluride (ZrTe3) is a typical charge density wave (CDW) material with strong electrical and optical anisotropy compared with graphene, transition metal disulfides (TMDs), topological insulators (TIs), and black phosphorus (BPs). To date, the nonlinear optical properties of ZrTe3 and its applications in information photonics aspect have not been reported. In this work, the nonlinear optical saturable absorption properties of ZrTe3 nanosheets and their application in passively mode-locked fiber laser are systematically investigated for the first time. The results show that the modulation depth and saturation intensity are 6.5% and 89.87 MW/cm(2) at the optical fiber communication band (C band), respectively. In the erbium-doped fiber (EDF) ring laser with ZrTe3 nanosheets as saturable absorber (SA), a stable mode-locked pulse train is obtained with the central wavelength of 1562.12 nm, the 3 dB optical spectral width of 2.07 nm, the basic repetition rate of 3.377 MHz, and the pulse duration of 1.469 ps when the pump power is 65 mW. Moreover, the dynamic evolution process of the optical spectrum and pulse sequence under different pump power are illustrated. All results reveal that ZrTe3 has excellent potential for applying in many fields, including ultra-fast all-optical sampling, optical frequency comb, optical fiber communication, supercontinuum, etc, and provides an intuition of opening new avenues toward various advanced information photonic devices.