Incoherent optical modulation of graphene based on inline fiber Mach-Zehnder interferometer

We investigated the incoherent optical modulation of graphene based on an inline fiber Mach-Zehnder interferometer fabricated by splicing D-shaped fiber and single mode fibers. Single layer graphene was covering on the D-shaped fiber face. With a backward pump-probe setup, we found that the incoherent optical modulation was independent of the wavelength difference between pump and probe laser, supporting theoretical analysis that the incoherent optical modulation is mainly contributed by the carrier-phonon process of graphene. Further, both the decrease of the pump wavelength and the increase of pump power would deepen the modulation in an exponential trend.