Structural Stability and Saturable and Reverse Saturable Absorption of Femtosecond Laser-Patterned MoS ₂

Molybdenum disulfide (MoS2) possesses excellent light–matter interaction intriguing for electronics and optoelectronics applications. However, precise MoS2 fabrication poses major challenges demanding high-temperature inert furnaces alongside the time-consuming process. Femtosecond (fs) laser fabricates with high precision owing to shorter (10–15 s) pulses inhibit heat transfer to vicinity. 0.25 and 0.5 molar ratios are more suitable for MoS2 fabrication, and the structural characteristics confirm the successful fabrication of fs laser-patterned MoS2 in the 2H bulk phase. The wettability analysis manifests good hydrophilic behavior suitable for heterostructure fabrications. Thermogravimetric analysis and systematic annealing from 200 to 400 °C performed for 0.5 M of MoS2 reveals good thermal stability until 250 °C. The chemical stability was analyzed by immersing the 0.5 M sample for 5 days in pH-3 (HCL/H2SO4), which holds better stability than the pH-10 (NaOH) sample, leading to chemical modifications. The optical absorption examined using UV–visible DRS shows the characteristics of MoS2. The chemically modified pH-10 (NaOH) (CM-MoS2) sample exhibits the characteristics of MoO3 and MoS2 peaks which display enhanced absorption. It shows excellent photoluminescence (PL) emission by altering the negative trions recombination to excitons yielding a high PL quantum yield. The third-order nonlinear optical absorption investigations on ITO and 0.25 M MoS2 samples reveal saturable absorption (SA) behavior. The 0.5 M and CM-MoS2 samples show reverse saturable absorption behavior favoring optical limiting applications.