建構側邊鍍金波導管之表面電漿子Fabry-Perot量子點雷射

Abstract

本論文中，我們研究以量子點(QD)作為活性介質(active medium)並其以側邊鍍金波導的新型Fabry-Perot (FP)雷射，此雷射是由伊利諾大學莊順連教授團隊呂建嶢所設計製造。除了元件結構設計和製成方法有詳盡介紹外，我們對此型量子點電漿子雷射做了完整的理論分析和靜態實驗量測,並已觀察到雷射現象。我們以連續波(CW)和脈衝(pulsed)模式下，予電流灌注此雷射元件,並觀測其放大自發輻射(ASE)頻譜。從實驗觀測放大自發輻射(ASE)頻譜數據，我們探知此雷射於1287奈米波段受激發光，並可從放大自發輻射中萃取淨模增益(net modal gain)、變折射率(refractive index change)、線寬增強因子(linewidth enhancement factor)和群折射率(group index)。從實驗分析，我們於雷射波段附近萃得約0.35的線寬增強因子。低線寬增強因子對於高頻操作、降低光絲線像(filamentation)、自我聚焦(self-focusing)、展區射極體的反導(antiguidance)和調變下頻率變化(chirp)有極大的幫助。此外。我們於攝氏7-15度區段取得無限大的特性溫度(characteristic temperature)，這表示完全溫度不敏感的元件操作是可行的。於量子點電漿子FP雷射所得高群速度顯示側邊鍍金屬層提供波導導引機制的色散影響。本碩論實驗結果顯示，此已可實現的側邊鍍金屬量子點電漿子FP雷射是擁有對稱增益、降低線寬增強因子、高溫度穩定度和於高頻操作下低頻率改變，並且對未來奈米雷射研究有程度上得幫助。

A new laser structure consisting of quantum dots (QDs) as the active medium and gold-coated metallic waveguide, designed and fabricated by Professor Chuang’s group (Chien-Yao Lu) at the University of Illinois, is studied. The structure design and the fabrication of this device are introduced, and the lasing action is also observed. Both theoretical analysis and experimental measurements are performed on the optical characteristics of the QD plasmonic laser. The amplified spontaneous emission (ASE) measurements of a QD plasmonic FP laser emitting in the 1287 nm wavelength region are investigated. Our experimental study of the ASE spectra under different injection currents includes both continuous wave (CW) and pulsed mode bias conditions. From the ASE spectra, we can extract the net modal gain, the refractive index change, the linewidth enhancement factor, and the group index. Our experimental analysis reveals a low linewidth enhancement factor of about 0.35 at the lasing wavelength, which is helpful for high-speed operation, reduced filamentation, self-focusing, anti-guidance in broad-area emitters, and reduced chirp under modulation. Furthermore, we observed an infinite characteristic temperature T0, in the range of 7 to 15oC, indicating completely temperature-insensitive operation is possible. The observed high group index in the QD plasmonic FP laser indicates that the sidewall-coated metal layers contribute to the dispersion of the waveguide guiding mechanism. Our experimental results show that the metallic sidewall-coated QD plasmonic FP laser is a promising device with symmetric gain, reduced linewidth enhancement factor, high temperature stability, which has considerable potential for future high-speed reduced-chirp operation, and helpful for plasmonic nanolaser studies.