從變跡準相位匹配探討大頻寬綠光倍頻鈮酸鋰晶片之研製

Abstract

本論文主要以非線性晶體鈮酸鋰及摻氧化鎂鈮酸鋰為材料，藉由在晶體中研製出週期性極化反轉結構，產生一光柵動量，使1064nm紅外光因準相位匹配而倍頻輸出綠光。 吾人以高壓致極化反轉之方法，於0.5mm鈮酸鋰上完成變跡區段啁啾結構。憑藉本實驗室0.5mm鈮酸鋰之穩定製程，改良其步驟，以反向製程在厚度0.75mm鈮酸鋰上研製出一維週期性極化反轉結構。至於摻氧化鎂鈮酸鋰方面，吾人在厚度為1mm晶體上，利用定電流完成準一維一階綠光週期結構。為克服摻氧化鎂鈮酸鋰一維一階週期性結構製作上之困難，放棄傳統液態電極方式，使用高溫矽油加壓法，於0.5mm摻氧化鎂鈮酸鋰之表面研製出一維一階綠光週期性結構。光學量測上，於0.5mm鈮酸鋰變跡區段啁啾結構進行倍頻實驗，測得溫度頻寬

The thesis discusses the fabrication issues of periodically poled structure on congruent lithium niobate(CLN) and magnesium-oxide-doped congruent lithium niobate(MgO:CLN) to let a 1064nm infrared laser convert into a 532nm green laser by using the quasi-phase-matched second-harmonic-generation (QPM-SHG) technique. The apodized segment of chirped grating in 0.5mm thick congruent lithium niobate was fabricated by the forward electric poling method. A backward electric poling process were applied to make one dimension periodically poled structure on 0.75mm thick CLN. For MgO:CLN, We achieved a quasi-one-dimension first-order QPM periods on 1mm thick crystal by using a method of constant-current electric poling. In order to solve the merge on magnesium-oxide-doped congruent lithium niobate, we developed a method of high temperature electric poling, to make a surface of one dimension periodically poled grating on 0.5mm MgO:CLN. The SHG characteristics for an apodized-segment-chirped 0.5mm congruent lithium niobate shows acceptance temperature bandwidth 63 oC with conversion efficiency 36.6