量子點雷射雙能態放光暫態特性與光激發調變之研究

Transient Responses of Two-State Lasing and Optical Modulation in Quantum-Dot Lasers

吳昇展(Sheng-Zhen Wu)

指導教授 ： 毛明華

國立臺灣大學/電機資訊學院/電子工程學研究所/碩士(2007年)

https://doi.org/10.6342/NTU.2007.01100

摘要

量子點雷射在雙能態激發放光上的行為近年來一直是研究上熱門的題目，在將其雙能態激發放光特性應用在元件上之前，了解背後的物理成因與影響是首要的工作。
我們藉由分析量子點雷射在雙能態激發放光時候的動態特性，發現均勻寬化在一電灌注電流之後對基態增益有相當重大的影響，所造成極長的鬆弛時間是我們在動態上觀察到極長啟動延遲的主因，這樣的效應普遍在所有的量子點雷射雙能態激發放光樣品中被觀察到。
另外，在電訊號結束之後均勻寬化效應排除後，我們也觀察到基態增益回覆的現象，說明在電流灌注底下，操作在增益飽和區的基態受均勻寬化影響甚大。
藉由外界光激發的方式發現，在砷化鎵吸收產生的大量自由載子會吸收量子點雷射的基態激發光，甚至使基態出現暫時中止激發放光的行為出現。以光激發方式作小訊號調變也得出合理的K值，顯示出光激發方式作小訊號調變的可行性。

關鍵字

量子點 ； 半導體雷射

並列摘要

The phenomena of two-state lasing has been the popular research in the past few years. Before applying the characteristics of two-state lasing in quantum dot lasers into application fields, studies of the fundamental mechanisms are very important.
By analyzing the behaviors of transient responses in two-state lasing, we observed the effects of homogeneous broadening strongly reduced the GS gain, and induced ultra-long relaxation time, and caused ultra-long turn- on delay.
While the current pulse was turned off, the effect of homogeneous broadening was also removed. Therefore, we observed that GS turned on again which implied the homogeneous broadening effect deeply affected the GS during current injection process.
By measuring the transient responses of the quantum dot laser pumped by a Ti:sapphire laser, the free carriers generated in the GaAs region absorbed the photons emitted from GS, and caused GS to stop lasing. We extracted a reasonable K-factor from the small signal modulation by optical excitation, which implied this kind of measurement is feasible.

並列關鍵字

Quantum Dot ； Semiconductor Laser

參考文獻

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