Research On Wide Band-Pass Filters Of Broad Angle Incidence Based On One-Dimensional Photonic Crystal

Photonic crystal is a new kind of synthetic material. It forbids propagation of photons in a certain range of frequencies known as photonic band gap, which is the most important property of photonic crystal. One-dimensional photonic crystal is made up of different materials periodically stacked in one direction. It is simple in structure and easy to fabricate, so it can be used to make different kinds of filters.Among the previous reports on one-dimensional photonic crystal, wide band-pass filters of broad angle incidence are rare. In this thesis, the following two filters are studied:1. Using ZnSe and Na₃AlF₆ as high and low refractive index materials, BK7 as substrate, the filter based on one-dimensional photonic crystal has a wide pass band in the joint area of visible and near infrared region, decent transmittance in the pass band at broad angle incidence ranging from 0°to 50°and obvious cut-off region at both sides of the pass band. The filters which are of both cut-off and pass properties at broad angle incidence have potential applications in photon-rejuvenation, CCD camera and so on.2. Using ZnS, Ag and MgF₂ as materials, BK7 as substrate, the filter based on one-dimensional metal-dielectric ternary photonic crystal has a wide pass band in visible region, good transmittance in the pass band at broad angle incidence ranging from 0°to 70°and it can block ultra-violet and infrared light. Such kind of filter can be used in display panel, digital camera, sensor protection and so on.The calculation of the properties of offers a theoretical prediction to the application of the filters in the related photo-electronic devices, which includes the following two aspects:1. The dispersion relation of one-dimensional binary and ternary photonic crystal is derived on the basis of the formation mechanism of photonic band-gap. Band-edge analysis is used to determine the position of the forbidden bands and investigate the influence of the incident angle and polarization on the band-edge and bandwidth, which shows the band-pass property of the filter. Compared with transfer matrix method, band-edge analysis gives a clearer and deeper physical implication that the periodicity of the structure is the key factor that causes the band-gap.2. Transfer matrix method is applied to numerically simulate the transmission spectra of the filter. The result proves the correctness of band-edge analysis shows the influence of the incident angle and polarization on the transmittance and indicates the satisfactory transmittance in the pass band at broad angle incidence.At the end of the thesis, the prospective work is briefly mentioned, including the fabrication of the filter and some technical problems to be solved.