鈮酸鋰 (LiNbO3) 晶體的非線性光學係數大，而且可利用高電壓對其進行週期性極化反轉而成為PPLN(Periodically Poled Lithium Niobate) 晶體。晶體的準相位匹配 (QPM, quasi-phase matching) 拓展了非線性光學晶體的應用範圍，且大大的提高了非線性光學轉換效率。而QPM-OPO所產生的近、中紅外光波段光源，可廣泛應用在軍事、環境監測、醫療、遠距離量測以及光譜學等各種領域。

為了產生高功率紅外光的波長，我們嘗試製作厚度1mm的PPLN晶體，採用兩階段極化反轉方法，不但成功地克服了鈮酸鋰晶體在高電壓(~22kV)製程下容易破裂的問題，且獲得一些重要的控制參數與現象解釋；而且，為了充分應用PPLN大截面積的優點，我們還設計了一個高功率的紅外光雷射架構。我們成功地製作出長度35mm，寬度5mm ,週期為29.6um之週期性極性反轉鈮酸鋰晶體，另外還測試了其非線性轉換效率。在光參數產生器結構，總轉換效率(訊號光加閒置光)可達到61.2%，可以證明我們所的製作的PPLN晶體的週期性很好。為了獲得最佳的輸出反射率，利用可旋轉的BK7材質坡璃片其Fresnel反射特性，用以模擬出不同的輸出反射率進行的光參數振盪器實驗，找到50%及75%　兩種輸出反射率。最後，我們將50%的輸出反射率直接鍍在PPLN上進行了光參數振盪器實驗，這些成果都是為了設計出一個高功率之紅外光波段光源而努力

The non-linear optical coefficient of Lithium Niobate (LiNbO3) crystal is great, and can utilize the high voltage to transfer it to PPLN (Periodically Poled Lithium Niobate) crystal. QPM(quasi-phase matching) technique enlarges non-linear optical coefficient and expands the applications in many domains such as military, environmental monitor, medical treatments, quantity examining, long distance measurements and spectroscopy…etc.

For producing high power infrared, one utilized two stages methods to fabricate 1mm thickness PPLN with period 29.6um. Not only one overcame the problems during high voltage poling (~22kV) and collected many valuable parameters, but proposed a high power infrared laser structure sufficiently used the advantages of this large cross section PPLN crystal. One had succeeded in fabricating 35mm-long, 5mm-width and 1mm thickness PPLN with the period is 29.6um. In OPG, at the 2 mJ pump pulse energy, it generated 829uJ and 395uJ pulse energy; 41.5% and 19.8% conversion efficiency at the signal and idler wavelengths, respectively. The total conversion efficiency of OPG process is about 61.2%. For getting best output coupler at signal wave, utilize whirling BK7 glass of its Fresnel reflection characteristic to simulate tunable output coupler reflection. One obtained two values, 50% and 75%. Finally, one has carried on a series of OPO experiments with different output coupler. All these efforts were for the sake of preparations for a high power infrared laser one proposed.

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