二維與三維砷化鎵光子晶體及其波導結構之製作與分析

Abstract

介電係數週期性排列的材料，部分波段會因破壞性干涉呈指數衰減，導致無法在此結構上傳播，此現象稱為光子能隙（photonic bandgap），此類具有介電係數週期性排列的結構則稱為光子晶體(photonic crystal)。在本文中，我們嘗試製作二維與三維光子晶體及其波導結構與共振腔，探討光子晶體濾波的特性。 二維光子晶體方面，製作出空橋式結構光子晶體，發現完美光子晶體結構在900∼940nm範圍內有光子能隙，且由CCD影像可看出光束行進方向，發現光子能隙波段有強烈衰減的現象。 三維光子晶體方面，利用自我複製法製作出三維面心結構光子晶體，再用側向濕氧化法氧化樣品，控制氧化時間使樣品未完全氧化製造出缺陷結構，設計兩種方法改變缺陷模態波長：1.控制氧化時間，缺陷面積越大，缺陷模態紅移，紅移範圍約為62nm；2.改變特徵尺寸大小，特徵尺寸越大，光子能隙紅移，缺陷模態亦紅移，紅移範圍可高達150nm。最後，我們分析了光子晶體缺陷模態與缺陷結構的關係，發現缺陷模態在缺陷結構處最為明顯，證實在頻譜中觀測到的缺陷模態，確實與所製作的缺陷結構有關。

In some materials with periodic variation of dielectric constants and light within a certain frequency range shows exponential decay due to destructive interference and cannot propagate. This phenomenon is called photonic bandgap and this kind of structures is called photonic crystals. In this work, we fabricated two- and three-dimensional photonic crystals and their waveguide structures. In two-dimensional photonic crystal study, air-bridge type photonic crystals have been fabricated. We demonstrate that there is a photonic bandgap from 900nm to 940nm. Light cannot propagate in this wavelength region and this phenomenon was shown by CCD camera. In three-dimensional photonic crystal experiment, we fabricated defect mode structures by controlling the oxidation time. We design two parameters to change the wavelength of defect mode, i.e., the defect size and the feature size. With increasing defect size and feature size, we observed the red-shift of defect mode and the wavelength shift are 62nm and 150nm respectively. Finally, we analyzed the relationship between the defect modes and s defect structures. The defect mode is most obvious where the defect structure is located. This confirms the relation between the defect mode and defect structure.