Graphene is a two-dimensional material, manifestsgood photoelectricity performance and flexible tunability. Comparing withtraditional metal multilayers, graphene multilayers possess more advantages. The SPPs in graphene possess huge mode localization and low propagation loss in far infrared regions. Meanwhile, graphene manifestskerrnonlinearity.By taking advantage of graphene, the propagation of SPPs can be manipulated very well.
TheProf.Bing Wangofultrafast optics grouphas presentedthe nonlinear graphene multilayers composed ofarbitrary layers of grapheneto excite the supermodes of SPPs.Apart from the symmetric and anti-symmetric supermodes which exist in linear multilayer graphene waveguides, more asymmetric supermodes emerge in the nonlinear counterparts as the field symmetry is broken. All supermodes can propagate steadily in the structure with the mode profile remains fairly constant. There is a certainthreshold of field intensity for the emergence of each individualasymmetric supermode. The dependence of the intensity threshold to yield asymmetric supermodes on the wavelength and chemical potential is also discussed. The study may find applications in developing all-optical converters and switches on the deep-subwavelength scale.
This work is supported by the 973 Program (No. 2014CB921301), the National Natural Science Foundation of China (Nos. 11304108 and 11674117), and the Specialized Research Fund for the Doctoral Program of Higher Educationof China (No. 20130142120091).
Fig. 1.(a) Mode profiles of four supermodes asN= 3. (b) Mode profiles of six supermodes asN= 4.
Fig.2.Electric field intensity distribution of the supermodes in the nonlinear graphene multilayer asN= 4.
