  We report the interesting possibilities related to the plasmonics and the key
parameters of optoelectronics, such as the absorbance and the transmittance, in
Van der Waals heterostructures of graphene monolayer on 2D transition metal
dichalcogenide (GrTMD) substrate here. We obtain the gapped bands with a Rashba
spin-orbit coupling dependent pseudo Zeeman field due to the interplay of
substrate induced interactions. This enables us to obtain an expression of the
dielectric function in the finite doping case ignoring the spin-flip scattering
events completely. We observe that the relative strength of screening is nearly
a constant with relative to the changes in the the carrier density.The stronger
confinement capability of GrTMD Plasmon(tunable)compared to that of standalone
graphene is a major outcome of our analysis;the plasmon dispersion yields the
q2/3 behavior and not the well known q1/2 behavior. We also find that the
absorbance and the transmittance are increasing functions of the frequency and
the gate voltage. This outcome is useful for devices utilizing
photoconductivity and the photo-electric effect.
