The unique optical and electronic properties of graphene allow one to realize active optical devices. While several types of graphene-based photonic modulators have already been demonstrated, the potential of combining the versatility of graphene with sub-wavelength field confinement of plasmonic/metallic structures is not fully realized. Here we report fabrication and study of hybrid graphene-plasmonic modulators. We consider several types of modulators and identify the most promising one for light modulation at telecom and near-infrared. Our proof-of-concept results pave the way towards on-chip realization of efficient graphene-based active plasmonic waveguide devices for optical communications.
We investigate experimentally and numerically the efficiency of surface plasmon polariton excitation by a focused laser
beam using gold ridges. The dependence of the efficiency on geometrical parameters of ridges and wavelength
dependence are examined. The experimental measurements accomplished using leakage radiation microscopy. The
numerical simulations are based on Green's tensor approach.
KEYWORDS: Signal to noise ratio, Optical fibers, Refractive index, Reflection, Structured optical fibers, Single mode fibers, Near field scanning optical microscopy, Near field, Signal detection, Near field optics
Scanning near-field optical microscopy (SNOM) in reflection is employed for high-resolution mapping of surface
refractive-index distributions. Two different single-mode optical fibers with step-index profiles are characterized using a
reflection SNOM setup, in which cross-polarized detection is employed to increase the contrast in optical images and,
thereby, the method sensitivity. The SNOM images exhibit a clear ring-shaped structure associated with the fiber stepindex
profile, indicating that surface refractive-index variations being smaller than 10<sup>-2</sup> can be detected. It is found that
the quantitative interpretation of SNOM images requires accurate characterization of a fiber tip used, because the
detected optical signal is a result of interference between the optical fields reflected by the sample surface and by the
fiber tip itself. The possibilities and limitations of this experimental technique are discussed.