具耳語廊模態之光子晶體共振腔元件特性之研究

Abstract

耳語廊模態所具有的高Q值與其多方向性共振是十分適合整合於積體光路中作為光源或具有特定功用的被動元件。在本論文中，我們設計、製作、量測並分析各種具有耳語廊模態的光子晶體共振腔元件特性，並探討其可能的應用。 論文一開始我們介紹了二維光子晶體共振腔元件相關的研究方法，包括數值模擬、製程技術以及量測系統。首先，本論文基於一種八對稱準光子晶體設計具有耳語廊模態的奈米共振腔，並在有限時域差分模擬與實驗上探討耳語廊模態的雷射特性、旁模抑制機制以及極小的元件尺寸。此外，論文中也探討一種新穎且具有等向均勻性光能隙的環形光子晶體，並設計出具有高Q值耳語廊模態的微共振腔雷射元件。 利用具有高對稱性的十二對稱準光子晶體晶格，我們設計具有高Q值的耳語廊模態雷射共振腔，並探討模態對共振腔邊界的強烈依存性，同時我們也進一步設計並探討多共振腔耦合的雷射元件。而由於耳語廊模態的分佈特性，吾人可以在該共振腔下製作一奈米柱作為電激發結構中的電流導路以及散熱器。透過製作不同尺寸的奈米柱，我們在模擬與實驗上探討由奈米柱所造成耳語廊模態的光學衰減與熱導改善特性。 基於整合在一般光子晶體積體光路的理由，我們將準光子晶體共振腔的共振腔邊界移植到一般光子晶體共振腔中以增強其中的耳語廊模態。藉由耳語廊模態的存在，我們探討了在不同共振腔-波導耦合排列下的均勻光耦合特性。而在應用上，我們提出並探討將此共振腔設計於雙層結構上，以作為高靈敏度光學應力偵測器的可能。最後，我們在正方晶格光子晶體上設計一具有最低階耳語廊模態的奈米共振腔，此耳語廊模態在具有較小模態體積的同時，同時具有較大的共振腔下奈米柱容許度。

Whispering-gallery (WG) mode with high quality (Q) factor and multi-directional resonance is very suitable for serving as the active laser sources and passive devices with specific functionalities in photonic integrated circuits (PICs). In this dissertation, we design, fabricate, and characterize various photonic crystal (PhC) based micro- and nano-cavities with high Q WG modes. The possible applications are also investigated and discussed. In the beginning of this dissertation, we introduce the related research resources for researches on two-dimensional PhC cavity devices, including numerical simulation methods, nano-fabrication processes, and measurement systems. At first, we propose a nanocavity design with WG mode based on 8-fold quasi-PhC (QPhC). Various WG modal properties are addressed both in experiments and simulations, including single mode lasing actions, side mode reduction mechanism, compact device size, and so on. Besides, we also investigate a novel circular-PhC (CPhC) lattice structure with isotropic photonic band gap effect and characterize the designed CPhC microcavity with high Q WG mode. By using 12-fold QPhC lattice structure with high symmetry, we design a microcavity with high Q WG mode. WG mode lasing actions and the strong mode dependence on microcavity boundary are confirmed. Due to the WG mode field distribution, we insert a nano-post beneath the microcavity to serve as the current injection pathway and heat sink in electrically-driven structure. By fabricating microcavities with different nano-post sizes, we investigate the WG modal loss behaviors and heat sink improvement due to nano-post both in experiments and simulations. For the purpose of integration in PhC-based PICs, we project the 12-fold microcavity boundary on a PhC microcavity and enhance a high Q WG mode in it. Due to the presence of WG mode, we investigate the uniform coupling properties of different waveguide-cavity geometries. In applications, we propose a double-layered structure based on above PhC microcavity and investigate its possibility in serving as an optical stress sensor. In the end, we propose a nanocavity design with lowest order WG mode based on square PhC lattice. This WG mode can be with very small mode volume and large nano-post tolerance beneath the nanocavity at the same time.