▎ 摘　　要

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. (C) 2016 Optical Society of America