First principles study and experimental investigation of graphene-molybdenum disulphide nanocomposites based passive saturable absorber

• Main Authors: Halim, Siti Nabilah Mohd, Ahmad, Fauzan, Lokman, Muhammad Quisar, Sapingi, Husni Hani Jameela, Taib, Mohamad Fariz Mohamad, Nawawi, Wan Mohd Fazli Wan, Yahaya, Hafizal, Rahman, Mohd Azizi Abdul, Shafie, Suhaidi, Harun, Sulaiman Wadi
• Format: Article
• Published: MDPI 2022
• Subjects: QC Physics
• Online Access: http://eprints.um.edu.my/40847/

Research on hybrid graphene with other two-dimensional materials has gained considerable attention owing to their potential applications beyond single components. Through our first principles analysis via density functional theory, graphene-molybdenum disulphide (MoS2) demonstrated a band gap opening by 2 meV, from gapless graphene when MoS2 layer is introduced into the structure. The simulated graphene-MoS2 has a direct band gap situated at K point of Brillouin zone with preserved Dirac properties of graphene. The experimental studies on graphene-MoS2 also have been performed by preparing graphene-MoS2-chitin nanocomposite through facile liquid-phase exfoliation method. Apart from energy gap using Tauc relation, the physical morphology and nonlinear properties of the material were systematically characterized. Graphene-MoS2-chitin exhibits a modulation depth of 10.5%, which is lower than individual graphene but higher than individual MoS2. Further investigation on the material's performance was done by integrating the fabricated film into Erbium-doped fiber laser. Stable nanosecond pulse laser operation was realized with graphene-MoS2-chitin hybrid saturable absorber. The pulse width was measured to be 156.4 ns with repetition rate of 1.89 MHz, corresponding to a peak power of 56.13 mW and pulse energy of 8.78 nJ.