本論文中使用滑輪式環型共振腔(Pulley-type ring resonator)，以耦合波理論(Coupled mode theory)，設計具有較長耦合長度與波導錯位(Offset)結構的滑輪式環型共振腔，並以有限時域差分法(Finite-Difference Time-Domain Method, FDTD)模擬電磁波在共振腔中傳播情形，研究不同位置波導錯位之滑輪式環型共振腔的光侷限能力。發現錯位波導特定尺寸可以降低光行進時耦合區域的光損耗，減少耦合產生的模態不匹配程度，增加共振腔的光侷限能力，使滑輪式環型共振腔具有較高的品質因子。我們並研究共振腔之光損耗位置，觀察錯位式之滑輪式環型共振腔的光損耗區域，驗證錯位波導可以減少來自載波波導與環之間的能量不完全耦合，以及光行進時產生的傳波損耗與彎曲損耗。本論文可將一滑輪式環型共振腔的品質因子由83,261升高至113,150。 In this study, we investigated the pulley type ring resonator in which the length of coupling region is longer than that of the other type ring resonators. The mode fields between straight and curved waveguides may be mismatched inducing the energy loss. We propose to introduce an offset at the junction of the two waveguides to reduce the energy loss. The finite-difference time-domain method (FDTD) is used to solve the Maxwell’s equations in time domain. The electromagnetic field distribution (EMF) can be obtained by the FDTD method inside and outside the ring resonator. The result shows that the Q-factor of the pulley-type ring resonator using the waveguide offset can be improved from 83,261 to 113,150.
