Optically Tunable Filter Using Liquid Crystal Defect In 1D Photonic Crystal

With application of dense wavelength division multiplexing (DWDM) technology, optical fiber communication technology is developing rapidly, and all-optical networks will be more intelligent, flexible and configurable in the future. Tunable optical filter is a crucial element of modern optical telecommunication systems, so it requires the devices with higher and higher performance. Compared with other filters, tunable photonic crystal filter is superiority in tuning range, bandwidth and channel suppression ability. In this thesis, the design process of one-dimensional photonic crystals tunable filter has been numerically investigated, the main work is as follows:1. The dependences of transmissivity, forbidden band position and width as well as quantity, position and width of defect band on the structure parameters of 1D photonic crystal have been analyzed in detail by using Bloch theory and transfer matrix method(TMM).2. One-dimensional photonic crystal filters with different structures has been numerically analyzed using the TMM method. According to the dependences of the filtering properties on the structure parameters of 1D photonic crystals, an optimized approach to design filter is presented.3. The equivalence between expansion Jones matrix method and transfer matrix method is proved in the situation of non-distorted, pretilt angle of 0 degree when normal incidence. The characteristics of the filter were examined by numerical simulation. It is found that there exist design deviations in the tuning range and center, and uniformity of bandwidth. The origins for the deviations are revealed and the corresponding adjustment means are given. Finally, the effect of dispersive and thickness deviation of liquid crystal on wavelength drift is analyzed by analogy.