Polarization dependence of a graphene-optical fiber hybrid Mach-Zehnder interferometer

Graphene exhibits a particular optical polarization dependence property, which is that supporting optical polarization states of graphene can be readily altered through tuning the polarity of the imaginary part of its conductivity. The in-fiber Mach-Zehnder interferometer (MZI) possesses extremely high sensitivity to the surrounding refractive index through cladding modes. Combining graphene and the in-fiber interferometer, a graphene-optical fiber hybrid MZI is constructed. Depending on the graphene polarization dependence property, the interference wavelength of the graphene-optical fiber hybrid MZI expresses periodic drift with the in-fiber light linear polarization angle adjusting within 180°. Meanwhile, drift periods corresponding to different interference wavelengths are slightly different, which is primarily due to the superposition of the polarization dependence behaviors of different cladding modes. For different light polarization states, with the in-fiber optical power increasing, the interference wavelengths and contrast intensities of the hybrid MZI transmission spectrum show a polarization independent linear blue shift and a nonlinear decrease, respectively.