臺灣博碩士論文加值系統

這篇論文展示了一個藉由光學共振腔將頻率穩定度由一碘穩頻的Nd:YAG雷射轉移至一以MgO:PPLN為核心的光學參量震盪器上(OPO)。我們的光學共振腔是由兩面高反射率的凹面鏡所組成，並由一石英玻璃館來固定腔長。腔長特別選擇在錯開共振腔頻率的基礎模與高階模的長度，並且可以用一壓電材料微調。本實驗中先將共振腔腔體的長度穩定在碘穩頻的Nd:YAG雷射的頻率上，接著把OPO的signal beam的頻率穩在共振腔的腔長上。穩頻完成後，OPO signal beam的頻率穩定度得到了很大的提升，同時idler beam的頻率不跳模可調範圍也只由pump beam的不跳模可調範圍決定。
此共振腔預計將會擺在一由抽氣速率每秒兩公升的離子幫浦維持真空度的不鏽鋼真空腔中，以消除由環境帶來的擾動。在此架設之下，我們預期OPO signal beam的頻率不穩定度低於60 kHz，僅受限於碘穩頻Nd:YAG雷射的頻率穩定度。

We present a stability transfer from an iodine stabilized Nd:YAG laser to the Mgo:PPLN-based optical parametric oscillator (OPO ) system by using the method of optical transfer cavity. The construction of the cavity is using two high reflective flat-concave mirrors and a fused silica spacer, and the length of the spacer is chosen to avoid coincidence of the frequency of the higher-order modes with fundamental modes. The length of the cavity is controlled by an PZT, and is locked to an iodine stabilized Nd:YAG laser. The frequency of the signal beam of our PPLN OPO is then locked to the cavity. With the stabilization, the stability of the signal beam has a large improve and the mode-hop-free tuning range is then limited only to the mode-hop-free tuning range of the pump laser.
The optical transfer cavity is planned to be placed in a stainless steel chamber, which is continuously evacuated by a 2 l/s ion pump to suppress the effect of the variation of the surroundings, after the AR window of the chamber is ready. With the whole setup, we expect the frequency drift of the signal beam of OPO will be less than 60 kHz/h, limited by the stability of Nd:YAG laser.

Contents
Abstract i
致謝 ii
Contents iii
Table of Pictures v
Chapter 1 Introduction 1
1.1 Motivation 1
1.2 Frequency Stabilization Using Transfer Cavity 2
1.3 Organization of the thesis 3
Chapter 2 Basic Principles 4
2.1 Working Principle of Transfer Cavity 4
2.2 Modulation Transfer Spectroscopy 5
2.3 Frequency Modulation Spectroscopy [8] 6
Chapter 3 Experimental Setup 9
3.1 Experimental Arrangement 9
3.2 Laser Systems 10
3.2.1 Master Laser: Iodine Stabilized Nd:YAG Laser 10
3.2.2 Slave Laser: Optical Parametric Oscillator 13
3.3 Cavity System 14
3.3.1 Construction of the Cavity 14
3.3.2 The Feedback System of Transfer Cavity 18
Chapter 4 Results and Discussion 20
4.1 The stability of the master laser 20
4.2 Cavity transmission signal 21
4.3 The stability of the signal beam of OPO laser 24
4.4 The Mode-Hop-Free Tuning Range of the Idler Beam of OPO 24
Chapter 5 Conclusion and Future Work 27
5.1 Conclusion 27
5.2 Future Work 27
References 28

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