Sub-Band Gap Absorption and Optical Nonlinear Response of MnPSe3 Nanosheets for Pulse Generation in the L-Band.

Two-dimensional (2D) materials have attracted extensive attention for use in fiber lasers for pulse generation due to their unique nonlinear optical properties. While 2D materials with tunable band gaps hold promise as versatile saturable absorber materials, their L-band (long-band) pulse generation capability remains challenging. Metal phosphorus trichalcogenides (MPX3) have recently attracted the attention of researchers and shown potential for sub-band gap saturable absorption in the L-band due to their high diversity of chemical components and band structural complexity. Herein, high-quality MnPSe3 is synthesized and exhibits broad-band linear and nonlinear absorption with the modulation depth and saturation intensity of 5.4% and 0.295 MW/cm2, respectively. Moreover, a stable passive pulse generation in the L-band is demonstrated in a fiber laser. The wavelengths of the passively pulsed laser at different pump powers are recorded, featuring a fixed central wavelength located at around 1602 nm with a maximum output power of 19.54 mW. This research promotes the realization of L-band pulsed lasers based on 2D materials, inspiring further exploration of the unique properties of the MPX3 family.