High contrast optical detection of single graphenes on optically transparent substrates

Abstract

The use of graphenes relies largely on their optical detection with Fabry–Pérot type structures. We demonstrate here that optical reflection mode imaging with single graphenes on the bottom of a bare transparent substrate such as mica can provide a high contrast of more than 12% for visible light. This can be explained with the destructive interference of light reflected from the substrate-graphene and graphene-air interfaces, similarly to black soap films. Since the contrast is only weakly wavelength dependent, white light contrast of single graphenes is sufficiently high to be easily detected with a human eye. We argue that with the graphene on the bottom of the transparent substrate high contrasts for single graphenes can also be achieved on other transparent substrates exhibiting a broad range of refractive indices.