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The Propagation Property Of Electromagnetic Waves In Photonic Crystals And Chiral Media

Posted on:2006-05-26Degree:DoctorType:Dissertation
Country:ChinaCandidate:Z Y XiaoFull Text:PDF
GTID:1118360155460339Subject:Electromagnetic field and microwave technology
Abstract/Summary:PDF Full Text Request
In recent years, an important field on the study of electromagnetics is one about new material. Chiral media and Photonic Crystal are typically novel artificial materials. Chiral media is made of one handedness mixed into a matrix. One of the aspects characterizing chiral media is the phenomenon of optical activity. Photonic Crystal is composed of one kind of material in which another kind of material is periodically distributed and it has peculiar ability of inhibiting spontaneous radiation of atoms and controlling light propagation. They may bring about important potential in several scientific and technical areas. Therefore, Chiral media and Photonic Crystal have been paid great attention by many fields in the world since 1980s. In this dissertation, the propagation property of electromegenetic waves in Photonic Crystals and Chiral media is studied. Integrating Chiral media with Photonic Crystals, we study the property of chiral photonic band gap and several novel structures of Photonic Crystals are presented. The dissertation is classified into four parts stated as follows.Firstly, we present a new photonic crystal structure, which is composed of fractal Cantor multilayer with a defect embedded in its middle. Optical transmission matrix method is used to calculating the transmittance and reflectance. Compared with general Cantor multilayer, we find the new structure has wider stopband and shows a super narrow band in the middle of wider stopband. It can be served as a super narrow bandpass filter. The pass band obtained can be less than 0.5nm near the infrared 1530 nm. The optical transmission in the center wavelength is higher than 99 %. This means a very low insert loss. It is more superior to other kind narrow band filters. This kind of photonic crystal super narrow band optical filter may find applications in super dense wavelength division multiplexing for optical communications and precise optical measurement.Secondly, the formula of reflection coefficient of multi-layer chiral media is derived by non-symmetric transmission-line method. Then, it is applied to 1-D chiral photonic crystal structure, which is composed of thin chiral layers sandwiched by air. The results show that it is difficult to obtain photonic band gap for general dielectric when the contrast of two media refractive indices isn't large, and the reflection coefficient is small. However, for chiral photonic crystal, although the refractive index of chiral layer is small, the wave spectrum contains forbidden zones and the reflection coefficient from such a structure is found to be almost equal to 1, i.e., the wave is almost totally reflected through adjusting chiral parameter. Therefore it is easier to obtain an ideal photonic band gap.Thirdly, It has been arguing whether the chiral parameter of chiral media affects on the microwave absorbing characteristics. The different constitutive relations are used to analyze the reflection problem of metal-backed chiral layer. Some numerical results are presented. It can be seen that the reflection coefficients are identical with different constitutive relations when the macroscopic parameters are unified. The numerical results show that the permittivity and the permeability of host are modified when chirality is introduced, which affects on the reflection. The conclusion has significance to unifying differential views.Lastly, integrating Chiral media with Photonic Crystals, we study the property of chiral photonic band gap. This novel structure is composed of thin chiral layers sandwiched by air. The results show that it is difficult to obtain photonic band gap for general dielectric when the contrast of two media...
Keywords/Search Tags:photonic crystal, fractal Cantor constructure, transmission matrix method, filter, non-symmetric transmission-line, constitutive relations, chiral media, reflection and transmission coefficient
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