2003-08-012024-05-18https://scholars.lib.ntu.edu.tw/handle/123456789/705341摘要：光子晶體因週期性介電質結構之緣故，導致電磁波通過晶體時由於反射波對入射波造成干涉，發生所謂的頻溝現象，阻擋在某些頻率振盪之電磁波通過。由於光子與聲子之類比性，可推斷由彈性振動材料組成之週期性結構，在適當調整其材料常數後通過之聲波亦有頻溝現象存在，則將此類結構稱為聲子晶體。本計劃將延續91年度微週期結構表面波頻溝研究初探計畫，進一步探討聲子晶體內之波傳行為與頻溝現象。除延續平面波展開法分析外，亦將運用有限差分數值方法針對彈性波於聲子晶體內傳遞進行研究，並發展電腦叢集系統建立高速計算之能力，實現徹體波及表面波波傳之模擬。在微機電實驗方面，由第一年初探計劃執行過程中，發現微米級聲子晶體製程相當繁複且困難度甚高，此計畫將繼續探討可行之製程，並與數值模擬比較。計劃分二年執行，第一年擬規劃與建構個人電腦叢集，以應付聲子晶體龐大之記憶體與計算量需求。配合電腦叢集之建立，將二維聲子晶體表面波傳電腦分析程式（平面波展開法）平行化以提昇效率。第一年亦將建立一套適用於正交性材料的有限差分方程式，並發展吸收型邊界程式碼配合使用。<br> Abstract: There has been a growing interest in recent years in studying the man-made two-dimensional periodic structures of dielectric materials known as “photonic crystals.” A major reason for this is the fact that these systems exhibit forbidden frequency bands (photonic band gaps) extending throughout the Brillouin zone. In these regions, electromagnetic waves are absent along all directions since they are strongly reflected by the structure. The existence of band gaps can lead to numerous practical interests such as DWDM in the optical communication application. The analogy between photons and phonons suggests that band gaps would also be found in systems comprised of two materials with different elastic properties called “phononic crystals.” Acoustic waves propagating in such structures also exhibit band gaps and may find applications in the high frequency acoustic wave devices. This proposal is a follow-up of the first year’s pre-study on the phononic surface acoustic wave’s bandgaps. For further investigation of phononic crystals with defects, in this proposal, we will develop a finite difference based computer code for studying the phononic bandgaps. In the first phase, to minimize the computation time in calculating the wave bandgaps in phononic structures, PC cluster will be implemented. The computer code based on the plane wave expansion method for solving the surface bandgap problems which is developing currently will be transformed into the form that is suitable for running in the PC cluster. For analyzing phononic bandgap in structure with defects, a finite difference based numerical code will be implemented; in addition, the absorption boundary condition will be studied. In the second phase, we are going to use the numerical code to study the wave propagation in phononic structure with sharp bend. In the experimental part, high frequency SAW device will be fabricated and integrated to the phononic crystal to study the bandgap characteristics. Finally, the experimental results will be compared with that of the numerical results, and the potential applications will be discussed.聲子晶體週期性構表面聲波頻溝Phononic crystalsperiodic structuressurface acoustic wavesband gapsfinite difference