Broadband Optical Modulators Based on Graphene Supercapacitors
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Abstract
Optical
modulators are commonly used in communication and information
technology to control intensity, phase, or polarization of light.
Electro-optic, electroabsorption, and acousto-optic modulators based
on semiconductors and compound semiconductors have been used to control
the intensity of light. Because of gate tunable optical properties,
graphene introduces new potentials for optical modulators. The operation
wavelength of graphene-based modulators, however, is limited to infrared
wavelengths due to inefficient gating schemes. Here, we report a broadband
optical modulator based on graphene supercapacitors formed by graphene
electrodes and electrolyte medium. The transparent supercapacitor
structure allows us to modulate optical transmission over a broad
range of wavelengths from 450 nm to 2 μm under ambient conditions.
We also provide various device geometries including multilayer graphene
electrodes and reflection type device geometries that provide modulation
of 35%. The graphene supercapacitor structure together with the high-modulation
efficiency can enable various active devices ranging from plasmonics
to optoelectronics