  Graphene, the carbon monolayer and 2D allotrope of graphite, has the
potential to impact technology with a wide range of applications such as
optical modulators for high-speed communications. In contrast to modulation
devices that rely on plasmonic or electronic effects, MEMS-based modulators can
have wider tuning ranges albeit at a lower operating frequency. These
properties make electro-optic mechanical modulators ideal for reflective-type
display technologies as has been demonstrated previously with SiN membranes in
Interferometric MOdulator Displays (IMODs). Despite their low-power consumption
and performance in bright environments, IMODs suffer from low frame rates and
limited color gamut. Double-layer graphene (DLG) membranes grown by chemical
vapor deposition (CVD) can also recreate the interference effect like in IMODs
as proven with drumheads displaying Newton's rings. Here, we report on the
electro-optical response of CVD DLG mechanical pixels by measuring the change
in wavelength-dependent reflectance of a suspended graphene drumhead as a
function of electrical gating. We use a spectrometer to measure the wavelength
spectrum at different voltages, and find a good agreement with a model based on
light interference. Moreover, to verify that gas compression effects do not
play an important role, we use a stroboscopic illumination technique to study
the electro-optic response of these graphene pixels at frequencies up to 400
Hz. Based on these findings, we demonstrate a continuous full-spectrum
reflective-type pixel technology with a Graphene Interferometric MOdulator
Display (GIMOD) prototype of 2500 pixels per inch (ppi) equivalent to more than
12K resolution.
