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The Study Of Enhanced Absorption In Photonic Crystals With Lossy Materials

Posted on:2016-05-09Degree:MasterType:Thesis
Country:ChinaCandidate:B LiuFull Text:PDF
GTID:2191330461986230Subject:Condensed matter physics
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Since Yablonovitch and John proposed the concept of photonic crystals (PCs), people pay much attention to PCs since this kind of artificial microstructures has special ability to control the propagation of the electromagnetic (EM) waves. Generally, PCs can bedivided into all-dielectric PCs and metal-dielectric PCs. The most prominent property of PCs is the photonic bandgaps (PBGs) in which the EM waves are prevented to propagate. In contrast with two-dimensional and three-dimensional PCs, one-dimensional PCs attract more attention because of the simpler structures and easier manufactures. In this thesis, we study the one-dimensional multilayer structure experimentally and theoretically within the visible and near-infrared region. The main contents mainly include two parts which are the second and the third chapters.In the second chapter, we mainly investigate absorption properties of the heterostructurecomposed of metal films and dielectric PCs. In the recent years, a new type of surface localized mode, which is also called optical Tamm states, attracts much attention. Contrary to the conventional surface states, optical Tamm states not only can be excited for both TE and TM polarizations but also can be induced under the condition of the wave-vector locating inside the light cone. By this kind of optical surface states, the reflectance of the light may be equal to zero with the tunneling conditions so that the transmission or absorption of the light of certain frequency can be enhanced highly. In the recent years, people pay most attention to single and multiple absorptions of optical Tamm states theoretically. In this chapter, with ion beam sputtering and electron beam evaporation,we experimentally investigate the absorption properties of a heterostructure composed of a metallic film, a top-layer and a dielectric mirrors. The single and multiple near-perfect absorptions of light can be realized by changing the thickness of top-layer. Experiments are in good agreement with the simulations. Such structureswill be useful in designing sensitive singleand multichannel perfect absorbers, etc.In the third chapter, we study the enhanced absorption of the asymmetric PCs and symmetric PCs inserted with ITO film as the defect. The near-perfect absorption of defect modeisrealized in the asymmetric structure. For better comprehension of physical mechanism to realize the perfect absorption,the distributions of the EM fieldintensities at the defect wavelength are also calculated for above two structures.It is found that the localized EM intensities in the asymmetric structure are larger than those in the symmetric structure. Compared with the metals, doped metallic oxides have many advantages such as tunable plasmonic frequency and refractive index, etc. Therefore, it is significant to study the optical properties of the PCs containing ITO films.
Keywords/Search Tags:photonic crystal, perfect absorption, tunneling mechanism, defect mode
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