The Reasearch On Chiral Photonic Structure Based On The Effective Medium Theroy

The plane wave expansion method (PWE) is one of the most popular approaches used for calculating photonic bandgaps in photonic structure. There is an advantage for the effective medium theory (EMT) to solve the discontinuity at the boundaries of the inclusions. In fact, a photonic structure belongs to a kind of discontinuous materials.The aim of this thesis is to introduce a modified method- the chiral PWE method with EMT, which is based on the Maxwell equations and the chiral constitutive relation. The modified method can be utilized to study a chiral photonic structure. The fields were expanded into Bolch's plane waves while the electromagnetic parameters in the form of effective expression. This modified method is proved valid.First the band structure of photonic crystals is given based on the method. Then the effects of the electromagnetism parameter are investigated on the photonic bands, the influences of the permittivity parameter on the bands of the eigen-modes of general photonic crystal or chiral photonic crystal is presented, the dependent of the separation of bands on the type of the chiral photonic crystal is revealed. AtΓpoint, there is no difference between chiral photonic crystal and general crystal in the influence of permittivity on the band position. Finally, the polarized mode of photonic crystal (PC) and chiral photonic crystal fiber (PCF) is demonstrated. For some low-order modes, the optical intensity mainly focus on the core area and guided modes with quite pure circular polarization are revealed.