Propagation Properties Of An Optical Surface Plasmonic Waveguide With A Butterfly Air Core

With the development of society, information is increasing at a cerntain speed, and modern communication systems have to deal with vast amounts of data. In that case, the speed of processing information must be improved. However, the fundamental limitations started to be imposed on the existing electronic and optical technologies. With regard to the nm-sized electronic circuits, the propagation speed are difficult to rise further due to RC-delay times. Optical circuits having enormous information capacities are essentially u m-sized because dielectric is effected by diffraction limit. In recent years, it is fascinating to note that electromagnetic modes supported by metal-dielectric interfaces were found to be beating the diffraction limit while upholding the optical bandwidth. These modes, in which optical fields are coupled to electron oscillations, are usually called surface plasmon polaritons (SPPs) and are characterized by the wavelength that is always shorter than the wavelength in the dielectric, exhibiting thereby subwavelength confinement. Due to the realization of surface plasmonic circuits combining the compactness of electronics with huge bandwidth of optical networks, people have started to pay attention to the surface plasmonic waveguides (SPWs), and carries on the research.In this paper, the summary of surface plasmons, surface plasmon polaritons and surface plasmonic waveguides are present firstly, and the finite difference frequency domain (FDFD) method is introduces simply. Then the transmission characteristics of a surface plasmonic waveguide with a butterfly air core have been analyzed by using the full vector FDFD. We compare the propagation properties of our proposed waveguide with two kinds of different structure of waveguides. Finally, the dependence of the transmission characteristics on gain medium is discussed.The main contents include as follow.(1) A kind of surface plasmonic waveguide (SPW) with a butterfly air core is introduced, and its transmission performance is analyzed using the finite-difference frequency-domain (FDFD) method. The dependence of distribution of longitudinal energy flux density, effective index, propagation length and mode area of the fundamental mode with longer propagation length supported by this waveguide on geometrical parameters and working wavelengths are discussed. Results show that the longitudinal energy flux density distributes mainly in the upper and lower two sharp corners which are formed by four air core, and the closer to the sharp corner the stronger the longitudinal energy flux density. The effective index, propagation length and mode area of the fundamental mode can be changed with regulating the radius of circular air core, the lateral distance of the two rows cores as well as the longitudinal distance of two columns cores. Thus this kind of surface plasmonic waveguide can be applied to the field of photonic device integration and sensors。(2) With the same parameters, Compared with the SPWs which are composed of two and three circular air cores, our proposed SPW in this paper has better propagation properties.(3) The dependence of the transmission characteristics on gain medium is discussed. The analytical analysis and numerical simulation results show that the presence of the gain medium with higher dielectric medium can increase the field confinement and extend obviously the propagation length.These studies will provide some theoretical basis for the miniaturization and highly density of integrated optical components, and for the future practical application of optical communication and optical devices.