  Dynamic color modulation in the composite structure of graphene
microelectromechanical systems (MEMS)- photonic crystal microcavity is
investigated in this work. The designed photonic crystal microcavity has three
resonant standing wave modes corresponding to the three primary colors of red
(R), green (G) and blue (B), forming strong localization of light in three
modes at different positions of the microcavity. Once graphene is added, it can
govern the transmittance of three modes. When graphene is located in the
abdomen of the standing wave, which has strong light absorption and therefore
the structure's transmittance is lower, or when graphene is located in the node
of the standing wave, it has weak light absorption and therefore the
structure's transmittance is higher. Therefore, the graphene absorption of
different colors of light can be regulated dynamically by applying voltages to
tune the equilibrium position of the graphene MEMS in the microcavity,
consequently realizing the output of vivid monochromatic light or multiple
mixed colors of light within a single pixel, thus greatly improving the
resolution. Our work provides a route to dynamic color modulation with graphene
and provides guidance for the design and manufacture of ultrahigh resolution,
ultrafast modulation and wide color gamut interferometric modulator displays.
