Graphene Molybdenum Disulphide Research Articles

First Principles Study and Experimental Investigation of Graphene-Molybdenum Disulphide Nanocomposites Based Passive Saturable Absorber

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.

Design considerations of a surface plasmon resonance (SPR) based tapered fiber optic bio-sensing probe with graphene-MoS2 over layers

In this paper, we have reported the design considerations of a surface plasmon resonance (SPR) based tapered fiber optic sensor by coating a thin film of platinum on a tapered fiber core followed by graphene-molybdenum disulphide (MoS2) monolayers. The theoretical study is based on five-layer matrix model. To see the effect of graphene-MoS2 over layers, performance parameters in terms of sensitivity and detection accuracy are evaluated for four taper profiles viz. exponential-linear, linear, parabolic and quadratic along with the taper ratio. From results, we inferred that with increase in taper ratio sensitivity also increases while detection accuracy decreases monotonically. For the proposed sensor configuration, maximum sensitivity value is found to be 7.04 μm/RIU at taper ratio 2.0 for exponential-linear taper profile while maximum detection accuracy obtained is 16.7623μm−1, at taper ratio 1.0. Thus, the results show that by introducing additional graphene-MoS2 monolayers, the sensitivity of the proposed sensing probe is enhanced by more than 44% at taper ratio 2 as compared to the conventionally used SPR based fiber optic sensors coated with platinum only. Also, the effect of increasing number of layers of graphene and MoS2 on the performance parameters is evaluated and compared. The advantageous features of the graphene and MoS2 layers have also been discussed for bio-sensing applications.