摻雜氧化鎂鈮酸鋰之準相位匹配綠光倍頻雷射晶片研製

Abstract

本篇論文分為三個主要部分：準相位匹配與倍頻理論之介紹，週期性極化反轉摻雜氧化鎂共熔鈮酸鋰雷射晶片之研製，以及綠光倍頻雷射晶片之光學量測與特性分析。 理論部分描述非線性頻率轉換與準相位匹配理論。製程部分則以未摻雜的共熔鈮酸鋰上成功的高電壓致極化反轉法為基礎加以改良，在厚度為0.5 mm摻雜氧化鎂鈮酸鋰晶片成功研製出最小週期為最小週期為6.75 um之第一階二維、13.8 um之第二階一維及6.9 um之第一階準一維的週期性極化反轉摻雜氧化鎂鈮酸鋰雷射晶片，此雷射晶片可用於綠光倍頻之用。在光學實驗部分，以波長為1064 nm之奈秒脈衝雷射進行綠光倍頻實驗，並嘗試拓寬其溫度頻寬，目前已成功研製出具有30 ℃溫度頻寬，在100 MW/cm^2之奈秒泵浦條件操作下之出光效率約在10.54 %，長度為0.8 mm的綠光倍頻雷射晶片，在250 mW的基頻光入射有26.4 mW的綠光出光。

This thesis is organized into three parts：(a) The theory of quasi-phase-matching (QPM) and second harmonic generation (SHG), (b) The fabrication techniques of periodically poled magnesium-oxide-doped congruent lithium niobate(MgO:LiNbO3), (c) Optical measurement and characteristic analysis of periodically-poled MgO:LiNbO3 laser chips for producing second harmonic generation (SHG) of green laser. First, the theory of QPM and nonlinear optical generation will be introduced. In the second part, the fabrication technique improvements are based on electric poling method of congruent lithium niobate. This method leads to the realization of periodically poled QPM structures of 0.5 mm thick MgO:LiNbO3 substrates. The smallest periods achieved in this work are (i) 6.75 um for the 1st 2D、(ii) 13.8 um for the 2nd 1D and (iii) 6.9 um for the 1st quasi-1D QPM device. These chips are suitable for producing SHG green laser. Finally, a green laser made of 0.8 mm long periodically poled MgO:CLN are tested by a pulsed 1064 nm laser of 100 MW/cm^2. The device exhibits a broad temperature acceptance width of 30 ℃ and SHG efficiency of 10.6 %, which yield 26.4 mW green at 250 mW 1064 nm pump.