Study On The Properties Of One-Dimensional Photonic Crystals For Optical Communication

Photonic crystal is a new type of artificial optical material whose refractive index changes periodically.It allows electromagnetic wave with certain frequency propagating in it and has characteristics of photonic forbidden band and Anderson states.One dimensional photonic crystal has received much attention because it can be made easily due to its simple structure.In this thesis,optic properties of Cantor multi-layers has been studied by means of transfer matrix method and scalability and sequential splitting properties of the spectra have also been discussed.Triadic Cantor multilayer with N=3 is considered as a photonic crystal composed of two kinds of dielectric materials stacked 27 layers.The optical thickness of each layer is equal toλ₀/4.Firstly,a new structure is obtained by replacing the dielectric material from the 11th to 15th layers with five layers another material whose optical thickness of each layer isλ₀/5.Filtering properties of the new structure have been studied.It is shown that the new structure has wider band gap and a super narrow transmission window appears at the position of centre wavelength.The full width at half maximum of the window is only 0.2nm when the central wavelength is equal to 1550nm.It means that the new structure takes on excellent super narrow filtering effect.Secondly,a new photonic crystal coupled resonator structure is obtained by replacing the material from the 13th to 15th layers with another material whose optical thickness is equal toλ₀/14.The results show that the new coupled resonator structure also has wider band gad and a high transimission ratio window appears in it.The position of the supper narrow transmission window shifts with refractive index of the defect when geometrical thickness is fixed.If the refractive index of the defect can be tunable,the new structure takes on excellent tunable filtering effect with wide band gap and tunable super narrow transmission window.It can be used as a widely tunable supper narrow filter which has important applications in super dense wavelength division multiplexing and precise optical measurement.Finally,a multilayer spatial structure is considered as a binary number be proposed by us.Within the framework of this approach propagation of classical waves and quantum particles can be treated as number recognition.A possibility is outlined to use the above approach for data storage.