Transmission Property Of Subwavelength Waveguides Made From Noble Metal And Nearly-zero-index Metamaterials

Metal-dielectric-metal (MDM) waveguide structures and zero index metamaterial(ZIM) are two sorts of nano-photonic systems with broad potential applications for theirability of overcoming the diffraction limit, confining and transporting electromagneticfields purposefully in nanoscale dimensions. In this thesis, basic waveguiding propertiesof these two sorts of structures are investigated and several ways to control thetransmittance of optical waves are proposed. Numerical simulation based on finiteelement method (FEM) is employed to verify these functionalities and to investigatesystematically and optimize corresponding characteristics.First of all, affects of side rectangular slot, triangular slot, semi-elliptical slot,semi-circular slot, and double semi-circular slots on the transmission spectrum of MDMwaveguides are analyzed. It turns out that side rectangular slots of different depths canbe used to realize filtering function. The filtering characteristics of three cascaded siderectangular slots and that of five are found to be able to work as a wide-band filter.Secondly, the existing condition and exciting manners of antisymmetry mode areinvestigated. Different modes exciting schemes are proposed according to the fielddistribution features of symmetry mode and antisymmetry mode. Not only symmetrymode and antisymmetry mode but also hybrid modes which are superpositions of thesetwo modes with different phases or amplitudes are obtained. The influences of siderectangular slot on the transmission spectrums of these modes are analyzed.In the end, the electromagnetic properties of ideal ZIM and photonic crystal ZIMare investigated. It turns out that the electromagnetic fields in ideal ZIM are quasi-staticand homogeneous. Incident waves could go into ZIM only when the incident angle isextremely small, while outgoing waves come out normally with respect to the interface,independent of the incident angle. The ZIM can be of total transmittance or totalreflection by changing the physical parameters or the surface character of embeddedinclusion(s).In conclusion, we show that side slots with different shapes can manipulate thetransmission spectrum of MDM waveguide. Furthermore, combination of multiple slotswith different depths could function as a filter. By changing the physical parameters ofembedded inclusions, the transmission property of ZIM subwavelength waveguide canbe manipulated. These regulation ways are promising to bring more interestingnanoscale photonics applications on high-density integrated platforms.