量子點雷射的模態競爭效應與反競爭效應

在這篇論文中，我們主要研究的題目是量子點雷射的模態競爭效應和反競爭效應。在第二章和第三章中我們研究了競爭效應的現象，控制長波長的強度，然後觀察長波長和短波長模態之間的競爭效應。接著我們改變長波長和短波長的波長，再去做競爭曲線，最後比較這些不同波長的長波長和短波長的競爭曲線。我們發現當我們改變兩個模態的波長時，它們之間強度變化曲線(競爭曲線)的斜率都是一樣的，而且都是負的。這代表當我們改變長波長的強度時，長波長和短波長之間只有競爭效應存在，而且不同波長對競爭曲線的斜率影響不大。我們利用雷射的速率方程式，來討論造成競爭效應的主要物理機制。並且詳細的討論量子點雷射的增益頻譜，均值增寬(homogeneous broadening)和非均值增寬(inhomogeneous broadening)的效應等等。在第四章中我們改變短波長的強度，然後觀察短波長和長波長的競爭曲線，我們發現此時競爭曲線的斜率有正有負，負的斜率代表競爭效應，而正的斜率則是代表反競爭效應。反競爭效應在過去的多重量子井雷射中已經被討論過了，但是在量子點雷射中的物理機制還沒有被討論過。由於量子點的大小分布是呈一個高斯分佈，所以會造成增益頻譜的非均值變寬。由於均值變寬和非均值變寬的作用，在量子點雷射中很容易產生反競爭效應，只要電流不要太高，慢慢降低短波長的強度到一定程度以下，就會出現反競爭效應。在這一章最後我們會討論反競爭效應的物理機制。此外我們還發現另外一種競爭效應，是過去文獻中沒有看過的，但在量子點雷射中很容易觀察到，這在第四章中會詳述。第五章是探討溫度效應所造成的模態競爭效應，由於溫度改變會影載子在1stES和GS的分布，所以長波長和短波長的模態會因為溫度變化，而有類似競爭效應和反競爭效應的現象，其物理機制和前面幾章是不同的。這一章內容的其中一部分，是我在國際期刊Applied Physics Letter發表的文章，刊登在2007年的volume 90 issue 18，題目是”Opposite temperature effects of quantum-dot laser under dual-wavelength operation”[55]。並且還有一篇也是投稿在Applied Physics Letter的文章，目前還在審核中，題目是 “Competition and anti-competition of laser modes in external-cavity quantum-dot laser system”

關鍵字

量子點雷射；競爭效應；溫度效應

並列摘要

In this master thesis, we primarily investigate the mode competition and anticompetition in quantum dot laser. In Ch2 and Ch3, we discuss the competition of laser modes between the long wavelength mode (LWM) and the short wavelength mode (SWM) when we control the intensity of the LWM. Then, we change the wavelengths of the LWM and the SWM respectively and do the same the measurement. The slopes of the competition curves are all negative and identical. This means that only competition effect exist between the SWM and the LWM. The different wavelengths of the SWM and LWM will not change the slope of the competition curves. We discuss the physical mechanism of mode competition by the laser rate equation. The laser gain spectrums of quantum dot lasers which have homogeneous and inhomogeneous broadening are discussed in detail in Ch2 and Ch3. In Ch4, mode competition and anticompetition between the SWM and the LWM are observed when we control the intensity of the SWM. Mode anticompetition occurs only when the intensity of the SWM decreases below certain level. Also we find another competition mechanism which is not reported in previous studies. The physical mechanism of competition, anticompetiton, and another competition effect will be discussed in detail in this chapter. In Ch5, The temperature induced mode competition and anticompetition are observed when the quantum dot laser is controlled to simultaneously oscillate at two wavelengths: the SWM and the LWM. When the temperature increases, the carrier distribution in the ground state and the first excited state will be changed. As a result, the relative intensities of the SWM and the LWM vary with the temperatures which are similar to the mode competition and anticompetition.

並列關鍵字

Quantum dot laser ； competition effect ； temperature effect

參考文獻

[7] 黃啟嘉，“光通訊波段之寬頻可調變半導體雷射，”台灣大學光電工程學研究所，2004。

[48] C.-F. Lin, Y.-S. Su, D.-K. Yu, and B.-R. Wu « Reducing Temperature Dependence of Semiconductor Lasers Using Nonidentical Multiple Quantum Wells,” Proc. Of SPIE Vol. 4651, 137 (2002).

[1] 蘇益信，“寬頻半導體光放大器與可調雷射，”灣大學光電工程學研究所， 2002。

[3] W. W. Chow and S.W. Koch, “ Theory of Semiconductor Quantum-Dot Laser Dynamics,” IEEE J. Quantum Electron. Vol. 41, 495(2005).

[4] C.-F. Lin, C.-C. Huang, F.-H. Chu, and Y.-S. Su, “Anticompetition of laser modes,” Appl. Phys. Lett. Vol. 82, 3611 (2003).

國際替代計量

量子點雷射的模態競爭效應與反競爭效應

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