High-Quality MoS2 Nanosheets: Synthesis, Strong Saturable Absorption and Potential for Nanophotonic Devices

High-Quality MoS2 Nanosheets: Synthesis, Strong Saturable Absorption and Potential for Nanophotonic Devices

This study reports the successful synthesis of high-quality monolayer and few-layer MoS2 nanosheets using the liquid phase exfoliation (LPE) technique. The prepared MoS2 dispersions exhibit a large population of these nanosheets, offering excellent potential for various applications.

The optical properties of the MoS2 nanosheets were investigated, revealing a strong saturable absorption (SA) response when subjected to femtosecond (fs) pulses at 800 nm. This significant SA behavior is characterized by an imaginary part of the third-order nonlinear susceptibility (Imχ(3)) of approximately 10^-15 esu, a figure of merit (FOM) of about 10^-15 esu cm, and a free carrier absorption cross-section (σFCA) of around 10^-17 cm2.

Further analysis estimated the induced free carrier density to be around 10^16 cm-3 with a relaxation time of roughly 30 fs. Notably, under identical excitation conditions, the MoS2 dispersions demonstrate a superior SA response compared to graphene dispersions.

The observed ultrafast nonlinear optical properties of the layered MoS2 highlight its enormous potential for advancing nanophotonic device development. Specifically, its strong SA behavior makes it a promising candidate for applications in mode-lockers, optical switches, and other ultrafast laser systems.

A key advantage of these exfoliated MoS2 dispersions lies in their high expandability. They serve as a versatile starting point for fabricating various derivatives, including filtered neat films, polymer composites, and functionalized composites. This adaptability allows tailoring the material's properties to meet the specific demands of diverse photonic devices and applications.

In conclusion, this research underscores the successful synthesis of high-quality MoS2 nanosheets and their exceptional saturable absorption properties. These findings pave the way for exploring the vast potential of MoS2 in the development of next-generation nanophotonic devices.