Artificial Electromagnetic Materials In The Subwavelength Integrated Optics Applications

Electromagnetic(EM) devices are experiencing physical size shrinkage and some effects can be realized using devices of tens of nanometers,which are much smaller compared to wavelength.It is expected that plasmonic,electric,and conventional photonic devices can be integrated on the same chip to take advantage of the strengths of each technology,or even that all-optical control of light can be realized on a chip by using the structured materials unavailable naturally.EM theory attracts a great deal of attention again,and the number of publications in this area is increasing exponentially. These achievement should be owed to the breakthrough development of the structured materials theoretically and experimentally in the past 20 years.In theory,photonic crystal first shows the potential ability of artificially structured EM materials to tune the EM wave.Photonic crystal displays distinct optical phenomena such as inhibition of spontaneous emission,high-reflecting omni-directional mirrors,photonic crystal fiber and one-way waveguide,amongst others.Matematerials have an ability to realize the double negative refraction by achieving simultaneously negativeεand negativeμat the same frequency domain.EM cloaking also has been observed using metamaterial with complex distribution ofεandμspatially.Unlike photonic crystal,for which the typical period is on the order of half of a wavelength, in matematerials all the properties mainly depend on the resonance of the single scatterer which is several time smaller than the wavelength so that homogenization can be carried out.In order to attain the application in the subwavelength integrated optics by manipulating the EM wave on the subwavelength scale,especially for EM wave in the optical communication wavelength range or the visible light region,surface plasmons are being explored for their potential and the candidate technology has been termed 'plasmonics'.Surface plasmons provide the opportunity to confine light to very small dimensions with exponentially decaying fields in both neighboring medium.The feature of surface plamons provides the possibility of localization and the guiding of light in subwavetength metallic structures,and it can be used to construct miniaturized optoelectronic circuits with subwavelength components.In experiment,recent advances allow material to be structured and characterized on the nanometer scale,this in turn has enabled us to explore the interaction between EM wave and artificially structured nanoscale material.Surface plasmons is confined to the surface of the metal.But the stronger the confinement is,the bigger the loss is because of the the metallic intrinsic absorption. Though the absorption of some noble metals like Au and Ag is the lowest for light wave,the loss in plasmonic devices made of them still significantly limits the application. Here we take metallic particle plasmon waveguides(MPPW) as an example. In MPPW,the reason that the guiding mode can exist is that metal particle can support the localized surface plasmon,which is a kind of subwavelength resonance.In fact,high index dielectric particle also can exhibit the subwavelength resonance and it is expected that the similar guided mode can occur in dielectric particle arrays due to near-field coupling between adjacent particles.But the absorption of some high index dielectric material is lower than that of the noble metals.Here we will explore the properties of dielectric particle arrays serving as waveguides which are highly desirable for the purpose of miniaturization and for their low-loss properties.The split-ring resonator(SRR) structures,together with many variants,have served in most cases as an essential constituent of electromagnetic metamaterials.SRR provides a negative magnetic permeabilityμnear magnetic resonance for some particular polarization of the incident wave.But until now,there is no rigorously analytic approach to determine the magnetic resonance frequency.Here a systematic study is presented on the magnetic resonance frequency of slotted circular cylinder resonator (SCCR) based on Mie expansion.An approximate empirical expression is also presented for magnetic resonance frequency of SCCRs from the viewpoint of an L-C circuit system.The rest of the paper is organized as follows.In chapterⅠ,we will give a general introduction to the related background knowledge.In ChapterⅡ,we will briefly introduce the multiple scattering theory implemented to solve the scattering problem.In chapterⅢ,we will study the high index dielectric particle waveguide based on multiple scattering theory.In chapterⅣ,we will investigate the magnetic resonance behavior of individual two-dimensional SCCR with finite thickness based on a rigorous full-wave approach.A summary is finally given in chapterⅤ.