Study On The Light Trapping And Filtering Of The One-dimensional Photonic Crystal In The Visible Region

The photonic crystal is a new man-made material, which is formed by dielectric materials with different dielectric constants distributing periodically in space. Many potential applications of photonic crystal, such as reflecting mirror, photonic crystal fiber, photonic crystal filter and polarizing film, are based on the characteristic of having complete band-gap, which is owing to modulating the light propagation in it.Since the one-dimensional photonic crystal has the advantages of more simple structures, easier to analysis, and can realize the same bandgap properties, comparing to two-dimensional and three-dimensional photonic crystal, it attract particular concern of the most scientists. In this paper, the research emphasis is studying the bandgap of periodicity and defect one-dimensional photonic crystal by using the plane wave expansion method and the transfer matrix method. Furthermore, the application of one-dimensional photonic crystal is also analyzed. The contents and results are displayed as follows:(1)In order to achieve the goal of light modulation effect, providing theoretical guidance for the design of optical devices, we analysized how does the refractive index of the dielectric materials, the filling ratio, the lattice constant, the period numbers and the incident angle of the light affect the properties of the periodically one-dimensional photonic crystal. Discuss the relationship between the characteristic of the defect mode in the one-dimensional photonic crystal containing a defect and the defect layer material, lattice constant and the angle of the incident light.(2)Since the absorption ratio of the thin-film silicon solar cells is quite low in the visible and infrared region, one-dimensional photonic crystal (A1/B1)m(A2/B2)n is designed by using the frequency domain overlapping in this paper. Through studying the forbidden band of photonic crystal along with the change of crystal structure parameters and the light incident angles, we found that this reflector has a large omnidirectional forbidden band located in the visible and infrared region, the reflectivity of the band is up to90%. The photonic crystal is applied to act as a reflector at the bottom of the solar cells, which can effectively improve the external quantum efficiency of solar cells.(3)The tunability of the PC filters relies on the modification of permittivity of the constituent materials, This scheme has a limited changing of the PC’s structure parameters resulting in quite narrow tuning range of the resonant peak, which is only several nanometers, that is too narrow to satisfy the various realistic applications. In order to solve this problem, one-dimensional photonic crystal [LiF/GaSb]3Air [LiF/GaSb]3with the air defect is designed. Adjusting the thickness of the air defect layer through mechanical methods, the tunning range of the filter is up to251.2nm in the visible region, the transmittance of the resonant peak is up to100%. And the wavelength of the corresponding resonant peak shifts approximately liner in the direction of long wavelength while increasing the air layer thickness, which can realize the precise adjustment of the conduction band.