Simulation study on the coupling behaviors of parallel photonic crystal slab structures
Date Issued
2004
Date
2004
Author(s)
Wang, Chih-Haw
DOI
en-US
Abstract
過去相關的光子晶體平板結構研究中，研究的內容著重於共平面光子晶體缺陷結構之間的相互作用。在本研究中，我們引進了平行光子晶體平板結構之觀念，來探討在全反射與光子晶體侷限效應共同作用下，共平面光子晶體與平行平板光子晶體結構耦合作用之差異。
我們先利用時域有限差分法來獲得單層平板光子晶體缺陷共振腔與線缺陷波導結構之光子帶隙結構，接著我們模擬得到平行平板光子晶體缺陷共振腔之頻率響應，且觀察電磁場在這種光子晶體垂直耦合中的場型與相位分佈，我們並探討耦合係數對於平板結構之間的距離及厚度的影響。
隨後，我們設計了一個由上層的缺陷共振腔與下層的線缺陷波導組成之光子晶體濾波器。我們變化上下兩層結構間的距離與缺陷共振腔之大小以得到濾波效率之變化趨勢。最後我們將所得到的結果與共平面光子晶體濾波器做比較，而發現垂直耦合結構中濾波效率改進了15.07 %，對此，我們提出了兩個可能的機制從事解釋。這種垂直方向濾波器的弁鈺N可應用在分波多工光纖系統中，尤其，當我們想發展三維的光子晶體元件積成時，上述的設計更顯得有用。
In the past research of photonic crystal slab structures, interest has been focused on the interaction between the co-planar photonic crystal defect structures. In this study, we introduce the concept of the coupling photonic crystal slab structures between parallel slabs. With the effect of both total internal reflection and the photonic band gap confinement, the differences between the coupling behaviors of a co-planar photonic crystal structure and a parallel photonic crystal slab structure are investigated.
We first use the FDTD method to evaluate the photonic band gap of the photonic crystal defect cavity and line-defect waveguide. Then, we obtain the frequency responses of the photonic crystal nano-cavities in parallel slabs and then investigate the field intensity and phase distributions. We study the dependence of the coupling coefficient on the slab spacing and slab thickness. Next, we design a structure composed of a defect cavity in the upper layer and a line-defect waveguide in the lower layer for channel dropping filter application. We vary the slab spacing and the size of the defect cavity to obtain the variations of the dropping efficiency. Finally, we compare our results with a co-planar channel dropping filter. We find that the dropping efficiency is improved by 15.07 % in using the vertical coupling scheme. We propose two possible mechanisms for interpreting these results. The operation of such a channel dropping filter should find applications in a WDM fiber communication system, particularly when 3D integration of photonic crystal device is needed.
Subjects
光子晶體
缺陷共振腔
濾波器
線缺陷波導
垂直耦合
photonic crystal
defect cavity
channel drop filter
vertical coupling
line-defect waveguide
Type
thesis
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