短腔光學參量振盪器與波長可調紫外光和頻產生之研究

Study of Short Cavity Optical Parametric Oscillator and Wavelength Tunable Sum Frequency Ultraviolet Generation

劉恩綺(En-Chi Liu)

指導教授 ： 彭隆瀚

國立臺灣大學/電機資訊學院/光電工程學研究所/碩士(2013年)

https://doi.org/10.6342/NTU.2013.01416

摘要

紫外光波段之非線性光學的頻率轉換為本論文的研究主題，依照準相位匹配理論，我們設計出光參振盪及和頻週期，並利用高電壓極化反轉技術，製作週期性極化反轉鉭酸鋰(Periodically Poled Lithium Tantalite , PPLT)非線性轉換光參晶體。我們在0.5mm厚的鉭酸鋰晶體(Lithium tantalite, LiTaO3, LT)基板，製作長度L=20mm寬頻紅外光結構；並利用0.35mm厚的鉭酸鋰基板，製作總長度L=25mm級聯式光參-和頻紫外波長可調和頻結構。
在光學實驗量測中，寬頻紅外光參產生採用單週期準相位匹配結構，以532nm作為泵浦光源，在簡併點附近進行光參轉換。我們利用光參振盪器波長輸出隨晶體溫度調整之特性，產生1000~1200nm光源。當輸入693mW綠光，可轉換出231mW紅外光，此時產生之紅外頻寬約38nm，斜線效率達59.35%。
對於厚度0.35mm之級聯光參-和頻晶體，我們藉由調整晶體溫度而改變第三階準相位匹配之紫外光波長輸出。當綠光泵浦功率為688mw下，可產生功率為1.2mW的348nm波長紫外光，斜線效率0.37%。

關鍵字

和頻 ； 紫外光 ； 紅外光

並列摘要

This work is the study of quasi-phase matching (QPM) ultraviolet frequency up-conver¬sion using periodically poled lithium tantalite (PPLT). It is composed of two parts：(1) design, implementation and characterization of optical parametric oscillation (OPO) with a single period first-order QPM structure on 0.5mm thick 20mm long PPLT, and (2) design, implementation and characterization of first-order optical parametric oscillation (OPO) structure of 19mm length cascaded 6mm long 3rd QPM-sum frequency generation (SFG) in the ultraviolet spectral regime using 0.35mm thick PPLT.
First, the PPLT OPO sample was fabricated a QPM period of 7.63μm. The device was characterized with a 532nm green pump and operated near the degenerate point. By temperature tuning, the device exhibit a broad spectral tuning range from 980nm to 1160nm. With a 532nm pump power of 693mw, we obtain infraed output power of 231mw with a slope efficiency of 59.35% and spectral width of 38nm at the crystal temperature of 130 oC.
Next, we characterized a second sample with cascaded structures to generate broadband IR beam and tunable SFG of UV light. Device has the same QPM-OPO periodic 7.63μm of length 19mm and a third-order QPM-SFG periodics of 6.098μm, 6.1071μm, 6.122μm, 6.135μm and 6.149μm of total length 6mm. In SFG design,we design five different periodics in cascade which allows us to get a tunable source of UV laser by crystal temperature tuning. At a green pump power of 688mw, we obtained a maximum power of UV laser about 1.2mw at a wavelength of 348nm and crystal temperature of 138.9 oC.

並列關鍵字

sum frequency generation ； ultraviolet ； infrared

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