熱原子的電磁波引發透明光譜及冷原子的四波混頻過程相位不匹配之理論研究

Theoretical Studies of the Electromagnetically-Induced-Transparency Spectrum in Hot Atoms and the Phase Mismatch of Four-Wave Mixing Processes in Cold Atoms

游秩群(Jr-Chiun Yu)

指導教授 ： 余怡德

國立清華大學/理學院/物理學系/碩士(2014年)

https://doi.org/10.6843/NTHU.2014.00400

摘要

本論文包含兩大主題。前一至四章主要討論「熱原子的電磁波引發透明光譜」；後五至七章則是探討「冷原子的四波混頻過程相位不匹配效應」。在第一個主題中，首先簡介電磁波引發透明效應(EIT)及其系統類型，並介紹了後續理論計算所需使用的兩條方程組OBE及MSE。第二、三章分別定性討論了Λ型及階梯型系統，在冷、熱原子下之EIT光譜特徵及成因。藉由推導描述曲線行為之各項重要參數的解析公式，使我們不僅掌握了各實驗參數於系統中扮演之角色，且對熱原子與冷原子系統間之差異，有了初步的認識，並有助於日後實驗之發展。
從第五章開始，將進入第二個主題。首先，我們對雙Λ系統下的四波混頻過程(FWM)及相位不匹配之效應做了初步介紹。於第六章，藉由調變系統單位長度之光學密度以及類比「準相位匹配」技術之週期性極化反轉結構的方式，為補償相位不匹配造成的能量耗損提供了解決之道。

關鍵字

電磁波引發透明光譜 ； 四波混頻 ； 相位不匹配

並列摘要

In this study, two themes are investigated: “The Electromagnetically-Induced-Transparency (EIT) Spectrum in Hot Atoms,” and “The Phase Mismatch of Four-Wave Mixing (FWM) Processes in Cold Atoms.”
First, EIT effect and their systematic types are introduced along with two equations, OBE and MSE, which are required for the subsequent theoretical calculation. Λ-type and Ladder-type systems are discussed qualitatively in regard to the properties and causes of EIT spectrum in both cold and hot atoms. By deriving a series of analytical formulas of important parameters that can be used to describe the curve behaviors, the role that each experimental parameter plays in the system is controlled, while at the same time a preliminary understanding of the difference between the hot- and cold-atom systems is acquired. The results have the potential to support the development of future experiments.
Second, the process of FWM and the effect of phase mismatch in a double Λ system are preliminary presented. By employing the methods of modulation of optical density per unit length and analogy with periodically poled structure of “Quasi-phase matching technology,” a solution to compensating energy dissipation caused by phase mismatch is discovered.

並列關鍵字

Electromagnetically-Induced-Transparency Spectrum ； EIT ； Phase Mismatch ； Four-Wave Mixing ； FWM

參考文獻

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