Few-layered ReS_2 as saturable absorber for 28 μm solid state laser

Abstract

A novel two-dimensional (2D) material member in the transition metal dichalcogenides family, few-layered rhenium disulfide (ReS₂) was prepared by liquid phase method successfully. By using the open-aperture Z-scan method, the saturable absorption properties at 2.8 μm were characterized with a saturable fluence of 22.6 μJ/cm² and a modulation depth of 9.7%. A passively Q-switched solid-state laser at 2.8 μm was demonstrated by using the as-prepared ReS₂ saturable absorber successfully. Under an absorbed pump power of 920 mW, a maximum output power of 104 mW was obtained with a pulse width of 324 ns and a repetition rate of 126 kHz. To the best of our knowledge, this is the first demonstration of applying ReS₂ in an all-solid-state laser. Moreover, this represents the shortest pulses in Q-switched MIR lasers based on a 2D material as the saturable absorber, which demonstrated the superiority of ReS₂ acting as an optical modulator for generating short-pulsed lasers. The results well prove that 2D ReS₂ is a reliable optical modulator for MIR solid-state lasers.