An anonymous reader writes: Researchers in China have shown that a graphene sheath can modulate light transmission thru an optical fiber at 200 GHz. The graphene, even crudely draped over the optic fiber on a microscope slide, absorbed some of the light passing thru the fiber. But a preceding short-wavelength light pulse could temporarily disable the effect, enabling an all-optical infrared fiber-optic switch. Recovery was fast enough to enable modulation of transmitted light at 200 GHz using conventional fiber-optic communication wavelengths and thinned commercial telecommunications fibers. The findings could have use in telecommunications industry and future high-speed on-chip optical interconnects.