Properties Of Coherent Thermal Emission Of One-dimensional Defective Periodic Structure

With the development of the nanophotonics in recent years, the extraordinary properties of thermal emission of nano-scale structure has caused great interest. This kind of structure has good prospects of application such as thermophotovoltaic system, energy conversion system, etc. Here in this paper we mainly study the properties of coherent thermal emission of one-dimensional(1D) photonic crystal with a defect.We make a study of the optical properties of 1D periodic structure with a non-absorbing defect. The length of the structure is finite. The impact of the thickness of the defect layer on the reflectance is studied, and the density of states of 1D periodic structure is given. The peak of density of states(DOS) does exist at the edge of the stopband of 1D band gap structure. The DOS is zero in the forbidden band. Whereas, there will be a peak of DOS in the forbidden band when a defect is inserted in the structure.We also analyse the optical properties of the finite-length structure with a absorbing defect, which is Silicon carbide. There are two kinds of method to insert the defect, one is straight doped and the other is that the defect replace one kind of the dielectric of the structure. We study the impact of the thickness of the defect and the emission angle to the emissivity, and the temporal and spatial coherence of the emission is discussed too. The quality factor that marks the temporal coherence and the angular distribution that represents the spatial coherence are given.In the end, we study the optical properties of the coherent thermal emission of the one-dimensional infinite periodic structure with a absorbing defect, which is Silicon carbide. The length of the periodic structure before the defect is finite, so that the electromagnetic wave can reach the defect and be absorbed. The great enhancement of emissivity is due to the localized defect mode and its coupling with the surface wave, which is excited at the interface between the defect layer and the infinite photonic crystals. We study the impact of the thickness of the defect layer and other parameters to the emissivity, the spatial distribution of the square of the electric field corresponding to the wavelength of the emission peak is also given. Besides, the impact of the defect mode to the emissivity and the coherence is analyzed too.