利用非線性光子晶體鉭酸鋰以級聯光學參量振盪器 之腔內倍頻架構產生多波長橘黃光雷射之研究

Abstract

本論文主要分為四部分:(1)非線性晶體與三波混成基礎理論，(2)週期性極化反轉鉭酸鋰(PPLT)之設計、製作與以遠場繞射的方法評量晶體結構，(3)利用樣品與優化腔鏡進行腔內倍頻的方式產生橘黃光雷射之光學量測，(4)利用樣品與多組腔鏡進行腔內倍頻橘光以進行特徵參數萃取的模型建構與模擬分析。 筆者利用鎳擴散製程與高電壓極化反轉技術製作週期性極化反轉鉭酸鋰樣品，並使用線性光學之遠場繞射實驗與模擬評斷週期性結構製作的好壞。晶體設計上，以先並聯光參結構後結啁啾倍頻週期結構的方式與532 nm綠光雷射達成準相位匹配之條件，使532 nm泵浦光以先光參轉換成1160/1180/1200 nm近紅外光後，再以倍頻轉換成多波長的580/590/600 nm之橘黃光雷射。 光學量測部分，以脈衝之泵浦光經過筆者製造之僅拋光研磨未鍍膜樣品與設計的共振腔結構成功地產生斜線效率為10%、低閾值12.94 MW/cm2的多波長橘黃光雷射。在後續更換三種腔鏡與一組樣品後進行量測，對多組實驗數據進行特徵參數的萃取與分析，並歸納出腔鏡優化的結論。 最後，以光參振盪器耦合方程理論、共振光場空間變化緩慢與穩態條件(steady state)為基礎，以入射平面波光場均勻與高斯分佈分別建構筆者實驗架構上的級聯光學參量振盪器之腔內倍頻架構產生橘光轉換器之理論模型。以Matlab進行數值計算與模擬，並將理論模型與實驗數據比較後發現實驗數據之信號光功率與產生橘光功率的結果與本研究提出之理論模型吻合。

This thesis is mainly composed of four parts: (1) Non-linear crystal and fundamental three-wave mixing theory, (2) Design and fabrication of periodically poled lithium tantalate, and the assessment of crystal quality using far-field diffraction, (3) Optical measurement of a sample by using the optimized cavity in the laboratory, and(4) Optical measurement by using another cavity in the laboratory and analysis of intra-cavity second harmonic generation(SHG) theory. The periodic structure for the ferroelectric domain is fabricated by using the high-voltage poling technique and then examined by far-field diffraction, which is supported by Fourier optics. A structure parallel to the optical parametric oscillator(OPO) cascaded by segment chirped SHG structure is designed. It is used to convert a 532 nm pump laser into 1160/1180/1200 nm wavelengths which are near infrareds. In addition, it can also be used to continuously convert 1160/1180/1200 into 580/590/600 nm wavelength orange-yellow lasers. The optical power is measured by using a muti-wavelength spectrum with a slope efficiency of 10% and a laser threshold of 12 MW/cm2. When the data are measured, the experiment is performed again using different cavities for comparison. The final step of this study is to propose a about theoretical model of the optical parametric oscillator cascaded by intra-cavity SHG structure, which is based on nonlinear optical coupled equations, resonant-light slowly-varying optical-field condition, and steady-state condition. Furthermore, the measured results are compared with those calculated by the theoretical model, and it was found the data figures are consistent.