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系統識別號 U0026-0602201017162300
論文名稱(中文) 銫原子中V-式的電磁引發透明
論文名稱(英文) V-Type Electromagnetically Induced Transparency in Cesium atom
校院名稱 成功大學
系所名稱(中) 物理學系碩博士班
系所名稱(英) Department of Physics
學年度 98
學期 1
出版年 99
研究生(中文) 張詠詠
研究生(英文) Yung-Yung Chang
學號 L2697401
學位類別 碩士
語文別 英文
論文頁數 60頁
口試委員 指導教授-蔡錦俊
口試委員-陳泳帆
口試委員-韓殿君
中文關鍵字 電磁引發透明  V 式 
英文關鍵字 Electromagnetically Induced Transparency  V-Type 
學科別分類
中文摘要 我們藉由實驗及理論的數值模擬來觀察並探討室溫銫原子的V式能階系統中所發生的多能態電磁引發透明現象。在實驗上,我們固定探測雷射的頻率,將其鎖在由基態|6 S1/2, F=3>到激發態|6 P3/2, F=4>的能階躍遷上,並使耦合雷射的頻率由基態|6 S1/2, F=3>到激發態|6 P3/2, F=2,3,4>的能階躍遷上掃動,則當耦合雷射的頻率正好滿足原子躍遷的頻率時,即可觀察到電磁引發透明現象。在理論的數值模擬中,我們由密度矩陣的方程式出發,並考慮綴飾態以及因為光激升而導致基態Zeeman次能階的原子從新分配的現象。從電磁引發透明的相對深度,我們瞭解到|6 S1/2, F=3>到|6 P3/2, F=2>的光激升扮演重要的角色,因為光激升會在|6 S1/2, F=3, mF=-3,3>造成不參與電磁引發透明的暗態。另外我們分析電磁引發透明的半高全寬,發現即使在弱探測光場下,其譜線寬度為超精細結構飽和吸收的三倍左右,所以可以推論探測光的穿透效應主要應來自電磁引發透明。綜合而論,我們的理論模擬與實驗數據有不錯的擬合結果。
英文摘要 We investigate the V-type electromagnetically induced transparency (EIT) in a multi-level system of cesium atoms at room temperature for both experimental observations and theoretical simulations. In this experiment, the frequency of the probe laser is locked at the selected cesium D2 transition,|6 S1/2, F=3> to |6 P3/2, F=4>, and the coupling laser scans across the hyperfine transition,|6 S1/2, F=3> to |6 P3/2, F=2,3,4>. The transmission of the probe beam can be detected while changing the frequency of coupling laser. The numerical simulations of each probed hyperfine level are derived from solving the steady state density matrix, using dressed atom approach and the population transformation due to optical pumping. We find that the optical pumping effect of the coupling field at the transition |6 S1/2, F=3> to |6 P3/2, F=3> produces two dark states |6 S1/2, F=3, mF=-3,3>. It plays an important role to influence the relative intensity of the EIT. Besides, the full width at half maximum (FWHM) of the EIT is about triple of the Doppler-free saturation absorption spectrum of cesium hyperfine transition even if the probe field is very weak. That is, the probe transparency due to the saturated coupling field, which simultaneously occur with the EIT in V-type system, dose not obvious in our experiment. The probe absorption spectrum from the numerical simulation fits well to the experimental profile.
論文目次 摘要 I
Abstract II
Acknowledgement III
Contents IV
List of Tables VI
List of Figures VII
Chapter 1 Introduction 1
Chapter 2 Theory 2
2.1 V-Type EIT 2
2.2 Dressed-atom Approach 4
2.3 Density Matrix Approach 10
2.3.1 Equation of motion of the density matrix 10
2.3.2 Interaction picture 12
2.3.3 Two level system 14
2.3.4 There level system 17
2.4 Optical pumping 20
Chapter 3 Experimental instrument and setup 23
3.1 Energy diagram 23
3.2 Experimental setup 24
3.2.1 Laser systems 25
3.2.2 Photomultiplier tube 26
3.2.3 Magnetic shielding 27
3.3 Doppler-free saturation absorption spectrum (DFSAS) 28
3.4 Frequency Control 32
3.4.1 Derivative signal 32
3.4.2 Electronic feedback 34
Chapter 4 Results and analysis 35
4.1 Numerical simulation in multi-level system 35
4.1.1 EIT 35
4.1.2 Doubly dressed state 37
4.1.3 Optical pumping 40
4.2 Analysis 45
Chapter 5 Conclusion 47
Appendix A 48
A.1 Two level system 48
A.2 Three level system 50
A.3 The simulation program 52
A.4 The fitting program 54
Appendix B 56
Reference 59
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