| In1968, Veselago showed theoretically that material with simultaneously negativeε and μ possess a number of unusual and often counterintuitive properties. If ε <0and μ <0, the vectors E, H and k form a “left-handed” triplet as k=E×H, andthe refractive index is negative using an extended snell’s law, i.e. n=εμ. The caseis referred to as negative-index materials (NIMs) or “left-handed materials”(LHMs).The NIMs have shown many novel properties, such as inverse Doppler effects, inverse erenkov radiation and inverse Goos-H nchen shift, and have many potentialapplications in superlens, new type Antennas, band gap materials and high-densityoptical memory et al. So this field has attracted great attention in optics, materialsengineering and microelectronics for decade. Nevertheless, no materials with ε andμ being simultaneously negative had been found in nature or demonstratedexperimentally prior to the year2000. Until now, the most works focus on the problemof the NIMs how to realize.The thesis is composed of three parts. In part one, the NIMs are achieved usingphotonic crystals (PCs), and the NIMs properties have been discussed in detail. In parttwo, the NIMs are achieved using doped perovskite oxides. Under magnetic field, thematerials show metal behavior below Curie temperature，i.e. Re ε <0. At the sametime, it can achieve Re μ <0during ferromagnetic resonance. The NIMs propertieshave been discussed in detail. In part three, we observed the inverse Doppler shift in aphotonic crystal (PC) prism for the first time, which has NIMs property at10.6μ mwavelength.Part One:1) A left-hand structure based on a two-dimensional (2D) PC with a negativerefractive index of–1has been proposed, and its imaging properties have beeninvestigated systematically.2) Naturally, planar waveguides based on photonic crystals cannot be of infiniteheight, and guidelines for the design of finite-height waveguides are, therefore,important for the realization of planar photonic crystal waveguides. Thephotonic band structures of finite-height two-dimensional photonic crystal slabs have been calculations. The results show that the height of PC slabs playan important role on the band structures. It provides a new way to design theNIMs.3) The model of tunable superparamagnetic photonic crystals self-assembled incolloidal magnetic fluids under externally applied magnetic fields isestablished. The photonic band structures of the guided modes propagating inthe PC slab have been calculated. The results that the tunable refractive indexmaterials can be achieved using magnetic fluids.Part two:1) The electronic structures of perovskite oxides were studied with the densityfunctional methods. Our calculations indicated that although the effects ofJahn-Teller distortion play a main role for getting the correct ground state, areasonable strong electron correlation correction is necessary for obtaining theexact band structure.3.5eV is a good choice for the on-site Coulombparameter U.2) The correlations between structural effects and egbandwidth in hole-dopedmanganites were studied with the density functional methods. The calculationresults show that the bandwidth exhibits an oscillating behavior as the Mn-Odistances shorten, and the Mn-O-Mn angles play a major role in the bandwidthvariation in these materials.3) The permeability and the permittivity of perovskite oxides were calculatedunder ferromagnetic resonance conditions. The negative refraction propertiesof the magnetic films have been discussed in detail.Part three:1) The PC prism, which has NIM property at10.6μm wavelength, has beendesigned. The experimental results show that the PC prism clearly exhibits anegative refraction behavior.2) The experimental setup for detection of the inverse Doppler effect has beendesigned. A clear criterion has been found to clarify the normal and anomalousDoppler effects. The experimental result clearly indicates that the observedDoppler effect is anomalous, and the inverse Doppler effect has been explicitlyobserved at optical frequencies for the first time. |
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