雙波長量子點雷射之模擬與分析

Simulation and Analysis of Dual-Wavelength Quantum-Dot Lasers

孫逸然(Sun, Leo)

指導教授 ： 林國瑞

國立交通大學/電機學院/電子工程系所/碩士(2019年)

摘要

本論文針對量子點雷射的連續出光與鎖模模式進行模擬與討論，我們建構一個適用於啁啾式量子點雷射的模型，分析並比較模擬與實驗結果。本研究討論的啁啾式量子點主動層能夠使兩種量子點基態能階同時產生雷射，有別於過去文獻雙波長雷射為量子點的基態與激態。模擬結果將分成連續出光與鎖模兩部分討論。連續出光模式使用的公式為速率方程式，從啁啾式量子點模型得到的光電曲線、光譜模擬的閾值電流和峰值波長與實驗結果相近。且雙基態雷射的光電曲線顯示，第二基態產生雷射後不會抑制到第一基態的雷射強度，與傳統均勻堆疊量子點明顯不同。鎖模模式使用的公式為時滯微分方程。模擬顯示吸收時間與頻寬限制參數為影響結果是否鎖模的主要參數。將公式結合啁啾式量子點模型，得到雙基態同時產生鎖模的結果，其脈衝振幅比例與實驗結果相近。因第二基態在時域上增益與損耗的差異大於第一基態，使得第二基態脈衝寬度小於第一基態。可知鎖模的模擬可以讓我們了解脈衝在時域上如何受影響，並可進一步推知鎖模脈衝的形狀、寬度等特性。

關鍵字

量子點 ； 雷射 ； 雙波長 ； 模擬 ； 速率方程式 ； 時滯微分方程

並列摘要

We construct a model which is applicable for chirped quantum-dot lasers’ simulation, the results are analysed and compared with experimental data, the chirped quantum-dot active layer in this research allows dual-GS lsing, which is different from the dual-state(ES&GS) laser in the references. The results will be discussed separately in two parts: CW and mode-locked mode. Equations for CW laser’s simulation are rate equations, the L-I curve and optical spectrum simulated by chirped quantum-dot model have similar threshold current and lasing wavelength compared with experimental results. The difference of L-I curve between ES+GS and 2GS lasing is that the ES lasing will inhibit the GS lasing, while GS2 lasing won’t inhibit GS1 lasing.Equations for mode-locked laser’s simulation are delay differential equations (DDE). Simulation results show that absorber time constant and bandwidth limiting element are parameters that deteremine whether the laser reach the mode-locked regime. We combine the DDE with chirped quantum-dot model, and obtain dual-GS mode-locking, the ratio of pulse peak power between two states are similar to experimental data. Because GS2 has larger differential gain, leads to a larger difference between gain and loss than GS1, causes a more abrupt mode-locked pulse and narrower pulse width than GS1. The simulation helps us gain insight of how the mode-locked pulse being effected in time domain, and be able to predict the characteristic of mode-locking such as pulse shape or pulse width.

並列關鍵字

Quantum-dot ； Laser ； Dual-wavelength ； Simulation ； Rate equation ； Delay differential equation

參考文獻

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