週期性極化反轉製程研究以及利用單一週期鉭酸鋰晶體產生紅光和藍光雷射

Study of Periodic-poling Techniques and Red, Blue Laser Generation Using PPCLT Crystal with single periodicity

蔡立酋(Li-Ciou Tsai)

指導教授 ： 楊士禮

國立清華大學/電機資訊學院/光電工程研究所/碩士(2008年)

https://doi.org/10.6843/NTHU.2008.00123

摘要

藍光及紅光雷射對於資料儲存、生物醫療及全彩顯示器上扮演重
要的角色。使用非線性光學晶體可改變入射光源的波長以得到藍光及
紅光光源，準相位匹(quasi-phase matching)技術的發展更近一步的
提高得到藍光和紅光雷射光源的效率。
本研究致力於製作週期性極化反轉之鉭酸鋰、鈮酸鋰以及鎂摻雜
鈮酸鋰晶體。在考慮材料本身製程的難易以及晶體光損害閥值，因此
選用鉭酸鋰晶體來產生藍光及紅光光源。為了得到良好的週期比例，
我們測試鉭酸鋰晶體的矯完電場、穩壓時間及其它製程上的參數，並
試了幾種不同的製程方式，最後利用高電壓極化反轉的製程技術並在
改變電壓的方法我們成功製作出週期漸變之鉭酸鋰晶體，其長度為4
cm，寬度0.55 cm，厚度為0.5mm。因此我們可以藉由改變入射光打入
晶體的位置來改變出來雷射光之波長。另外我們也量測此晶體的轉換
效率與可改變的波長範圍。在波長為532 nm及1064 nm的雷射光入射
下，可藉由和頻及差頻轉換產生波長為414 nm、670 nm和2592 nm之
藍光、紅光和紅外光雷射。 紅光的轉換效率約為29.5%，藍光效率約
為0.145%。在烤箱溫度為80 ℃下改變入射光進入晶體的位置其波長
從674.8 nm到676.8 nm。將來希望能達到更小週期的製程，以進一步
得到效率更好的藍光效率。

關鍵字

週期性極化反轉 ； 藍光雷射

並列摘要

The blue and red light lasers play an important role in data storage, biomedical and full colors display. We can use the nonlinear optic crystals to get the red and blue light lasers by changing the wavelength of the pump lasers. Moreover, the development of quasi-phase matching technology can make the enhancement of the efficiency to get the blue and red lasers.
The dissertation was devoted to fabricating the periodically poled lithium niobate, lithium magnesium-oxide-doped lithium niobate and lithium tantalite (PPLT) crystals. Considering about the difficulties in making the materials and the optical damage threshold of crystals, we choose the LT crystal to generate the blue and red lasers. In order to get better cycle ratios, we need to test LT on the coercive field, stabilization time and parameters on other fabrications. After testing under different circumstances, we had succeeded in fabricating 4 cm-long, 5.5 mm-width and 0.55 mm thickness fan out PPLT crystal by change the poling voltage. Therefore, we could change the wavelength of lasers by shifting the position where the pump laser hits into the crystal. When pumped with the 1064 nm and 532nm line, the crystal produces 670 nm and 2592 nm lines through optical parametric generation and 414 nm line through sum frequency generation. When the pump pulse energy is 2 mJ, the conversion efficiency of the red and blue light is 29.5%. and 0.145%. By shifting the position where pump laser hits into the crystal (the temperate of the oven is 80 ℃) the wavelength of the single is from 674.8 nm to 676.8 nm. It is hoped that we could get better efficiency of the blue light lasers in shorten cycle fabrication.

參考文獻

[2]Yasunori Furukawa, Kenji Kitamura, and Shunji Takekawa“Stoichiometric Mg：LiNbO3 as an effective material for nonlinear optics” , Optics Letters 23 1892 (1998)

[4] S. Ganesamoorthy , M. Nakamura, S. Takekawa, K. Terabe, K. Kitamura, S. Kumaragurubaran. “A comparative study on the domain switching characteristics of near Stoichiometric lithium niobate and lithium tantalate single crystals” Materials Science and Engineering B 120 (2005) 125–129

[5] 3-10. A. Kuroda, S. Kurimura, and Y. Ues：, Domain inversion in ferroelectric MgO:LiNbO3 by applying electric fields

Appl. Phys. Lett. 69, 1565(1996).

[6] Venkatraman Gopalana, Terence E. Mitchellb, Kurt E. Sicakfus：“Switching kinetics of 180° domains in congruent LiNbO3 and LiTaO3 crystals” Solid State Communications 109, 111(1999)