| Summary: | 碩士 === 國立臺灣大學 === 光電工程學研究所 === 92 === In the thesis, we study photonic crystal superprism devices and honeycomb photonic crystal fibers. Then we investigate tunable microcavities which can fill light and release light. The concept of tunable microcavities imitates the concept of the capacitances in circuits. We also analyze tunable Y-shape liquid crystal waveguides, and bring up an idea of polymer dispersed liquid crystal films with photonic crystal structures.
In the study of photonic crystal superprism devices, photonic crystal band structures are obtained by the plane wave expansion method. Then, photonic crystal dispersion surfaces are calculated. Propagation characteristics in the photonic crystal structures are determined. The deflections of light in photonic crystals are simulated by finite-difference time-domain method and the results are verified by the plane wave expansion method.
In the study of honeycomb photonic crystal fibers, in-plane band structures are solved and out of plane propagation relative bandgap sizes are plotted. The bandgap sizes can be enlarged with appropriate modification of honeycomb cells. Then, a guided mode pattern of the honeycomb photonic crystal fiber is plotted.
In the study of tunable microcavities, the photonic crystal band structures for the ellipse-rod-defects waveguides are calculated. The ellipse rods are rotated to switch the tunable microcavities.
In addition, liquid crystal devices are studied. The anisotropy of liquid crystals makes the cutoff frequency of guided modes in the photonic bandgap tunable. Liquid crystal defects become switches of light. Tunable Y-shape liquid crystal waveguides are simulated successfully. The concept of liquid crystal switches makes it possible to control the tunable microcavities by electric fields. We develop the extended plane wave expansion method and the extended finite-difference time-domain method for the anisotropic materials. Finally, polymer dispersed liquid crystal films with photonic crystal structures are proposed.
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