Passively Mode-Locked Solid-State Laser with Absorption Tunable Graphene Saturable Absorber Mirror

Two-dimensional layered materials have attracted huge interest in the generation of ultrafast laser for their excellent saturable absorption properties. However, it is still challenging to precisely control their saturable absorption properties. Here, by alternatively changing the electric field intensity on the surface of high-reflection mirror, we successfully control the nonlinear absorption properties (e.g., saturable fluence, modulation depth) of graphene-based saturable absorber mirrors (GSAM) at the optical telecommunication wavelength of 1.3 μm and their applications in solid-state lasers for the first time. Modulation depth of 1.2% is obtained from a GSAM with deposition of a λ/8 (λ = 1.3 μm) thick SiO₂ layer between the monolayer graphene and a high-reflection mirror, while modulation depth is increased to 4.3% with a λ/4 thick SiO₂ layer insertion in another GSAM. Pulses with the duration of 20 ps (λ/8 thick SiO₂ insertion) and 7.4 ps (λ/4 thick SiO₂ insertion) are achieved, respectively, based on the two mirrors. Our results indicate that this method is easy and reliable to versatility modulate the saturable absorption properties of other two-dimensional layered materials beyond graphene for the generation of ultrafast solid-state lasers.