Polarization modulation based on graphene-integrated Ex-TFG in thincladding fibre

Summary form only given. Light modulation by means of polarization management is crucial to avoid signal fading and errors in coherent optic communications [1]. In recent years, graphene has exhibited a great potential in light modulation due to its unique interaction with the electromagnetic field, and attracted increasing attention for applications in photonics and optoelectronics. [2-4]. To provide sufficient interaction length, an optical fibre with enhanced evanescent field generated by etched or tilted fibre grating structures [5, 6] is a promising approach. In this paper, we report an integration of multi-layer graphene onto an excessively tilted fibre grating (Ex-TFG, the tilted angle of ~82°) inscribed in thin-cladding fibre, and reveal its special polarization tuning characteristics. In the hybrid waveguide of graphene-integrated thin-cladding Ex-TFG, with strong and distinctive core-to-cladding mode coupling property, the grating can provide not only an accessible evanescent field for the enhancement of the light-graphene interaction, but also two sets of polarization-dependent cladding modes. As depicted in the upper part of Fig. 1(a), we can clearly see the two waveguide attenuation peaks corresponding to the TE and TM polarization status from the bare Ex-TFG. After the graphene coating, from the lower part of Fig. 1(a), we can observe that the larger change of coupling intensity in the TE mode and more pronounced wavelength shift in the TM mode, which attests to the polarization-dependent coupling and interaction with graphene