All-optical graphene modulator based on optical Kerr phase shift

Graphene-based optical modulators have recently attracted much attention because of their characteristic ultrafast and broadband response. Their modulation depth (MD) and overall transmittance (OT), however, are often limited by optical loss arising from interband transitions. We report here an all-optical, all-fiber optical modulator with a Mach–Zehnder interferometer structure that has significantly higher MD and OT than graphene-based loss modulators. It is based on the idea of converting optically induced phase modulation in the graphene-cladded arm of the interferometer to intensity modulation at the output of the interferometer. The device has the potential to be integrable into a photonic system in real applications.