在本論文中，我們使用的滑輪式環形共振腔 (Pulley-type micro-ring resonator)是經由耦合波導理論 (Coupled mode theory)計算後發展出來；由於環形共振腔相較於單點接觸式及跑道式環形共振腔有較長的耦合長度，能耦合進環內的光強度有所提升，這優點將使得滑輪式環形共振腔的品質因子 (Quality factor)較其他形式來得高。 我們經由設計耦合長度以及載波波導與彎曲波導間錯位結構的滑輪式環形共振腔，使用限時域差分法 (Finite-Difference Time-Domain Method, FDTD)結合等效折射率法 (Effective index approximation)模擬SOI (Silicon on isolator)基板上實際電磁波於波導中傳播情形，研究在載波波導與彎曲波導接合處進行不同程度錯位，發現能有效降低耦合區的光學損耗，減少耦合時產生的模態不匹配程度，達到臨界耦合 (Critical coupling)，進而增加侷限於環內光強度，使該共振腔具有較高的品質因子。 本論文將一滑輪式環形共振腔的品質因子由9180提升至11148，提升了約21.44%。 ;In this study, we dealt with the optimization of the micro-ring resonator, which is called pulley-type micro-ring resonator. The micro-ring resonator was developed based on the coupled mode theory. We adopted the finite-difference time-domain method (FDTD) to simulate the structure. By offsetting the junction of the straight waveguide and the curve waveguide at input and output port, it is found that the coupling loss can be reduced and the critical coupling can be achieved. We can enhance the confinement of the light propagating in the waveguide and the ring, which makes the Q-factor higher than the structure without offset. In the study, the Q-factor is increased from 9180 to 11148, which is 21.44% higher than the original one.
