以Cz法生長摻鎂鈮酸鋰單晶; MgO doped lithium niobate single crystals were grown by the Czochralski method.

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Title:	以Cz法生長摻鎂鈮酸鋰單晶;MgO doped lithium niobate single crystals were grown by the Czochralski method.
Authors:	鄭文翔;Wen-Hsiang Cheng
Contributors:	機械工程研究所
Keywords:	鈮酸鋰;鎂;極化;poling;LiNbO3;MgO
Date:	2008-07-07
Issue Date:	2009-09-21 12:04:33 (UTC+8)
Publisher:	國立中央大學圖書館
Abstract:	鈮酸鋰晶體是目前光電晶體種類裡面最常被拿來使用的光電材料，因此多年來研究繁多。然而，未摻雜共熔配比鈮酸鋰晶體受光折效應過強時影響會導致光損傷，通常可透過摻雜一些MgO或ZnO來降低損傷。而本實驗是以自行架設的柴式生長法(Czochralaki；Cz)生長出各種不同濃度(1、3、5mol%)的摻鎂共熔配比鈮酸鋰晶體(Congruent Lithium Niobate；CLN)，再利用極化(poling)處理使晶體的多疇結構(Muti-domain)，轉換成單疇(Single-domain)晶體。最後利用氣相傳輸平衡法(Vapor Transport Equilibration；VTE)將極化處理完的共熔配比的摻鎂鈮酸鋰晶體轉換成近化學計量配比摻鎂鈮酸鋰晶體(Stoichiometric Lithium Niobate；SLN)。從實驗結果發現，極化處理時在施加一定的電壓下，電流會漸漸上升至最大值，此最大值會在1.5~2.5mA/cm2，雖然摻鎂可以使晶體的抗光強度提高很多，然而經過VTE處理後的摻鎂鈮酸鋰，會隨著原本CZ生長摻鎂量的增加而使能經由VTE進入晶體內的鋰離子變少。對於摻鎂鈮酸鋰的性質檢測，我們使用UV 吸收光譜、FTIR 光譜與Raman光譜等光學儀器來確定其性質，並從結果中來討論其中的物理特性。 LiNbO3 crystals is used electrictel-opto materials in the electrictel-opto crystals, thus has been studied for many years. However, high-intensity single-beam photorefractive data on un-doped congruent LiNbO3 crystals show occurrence of a well-defind intensity threshold for optial damage of the output beam. This problem is doped MgO and ZnO. In the study, Magnesium (Mg) doped lithium niobate (LiNbO3) single crystals with different Mg concentrations were grown by the Czochralski method from a congruent melt composition. The electic field parameter to obtain single-domain crystals are presented in situ poling of crystals. Magnesium(Mg)-doped near-stoichiometric lithium niobate crystals (Mg:SLN) were prepared by the vapor transport equilibration (VTE) technique from Mg-doped congruent lithium niobate crystals (Mg:CLN). For the observation of experimenting result, the poling was carried out during growth by applying a DC electric field across the crystal-melt system with current densities varying from 1.5 to 2.5 mA/cm2. However, the doping concentration of Mg is hard to reach its second threshold in crystals grown by normal Czochralski technique. So, vapor transport equilibration method was employed to improve the [Li]/[Nb] ratio of Mg:LiNbO3 crystals. We investigate the optical properties of the crystal fibers form the equipments of UV absorption edge, IR absorption spectrum and Raman spectrum. We also discuss the physic characteristics from the measured optical properties.
Appears in Collections:	[Graduate Institute of Mechanical Engineering] Electronic Thesis & Dissertation

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