以電光非週期性晶格極化反轉鈮酸鋰晶體應用於雙波長雷射系統之腔內布拉格繞射元件之設計與研究

Aperiodic Poled Lithium Niobate Electro-optic Bragg Deflector as an Efficient Laser Q-switch in a Dual-wavelength Solid-State Laser

曾冠翔(Quan-Hsiang Tseng)

指導教授 ： 陳彥宏

國立中央大學/理學院/光電科學研究所/碩士(2011年)

摘要

布拉格繞射對於波長有敏銳的選擇性，對單一布拉格周期而言，僅可對單一波長產生繞射之效應(此處僅考慮第一階)。本論文中創新以模擬退火演算法，計算一非週期性結構，可滿足參銣雷射系統中兩種發射頻譜1064nm 與1342 nm 的繞射條件，在相同入射角度情況下，達到高效率且相同布拉格角度的繞射情形。
　　本實驗中，利用鈮酸鋰晶體良好的電光效應，以高電場週期性極化反轉的技術，將前述所計算的非週期性結構，製作於一長4公分，寬5釐米，厚500微米的鈮酸鋰晶體上完成該繞射元件的製作。
　　我們在外加最低z方向電場為120V時，量測到高繞射效率；1064nm 為93.5%，1342nm 為92.5%。進一步將其放置於Nd:YVO4固態雷射系統中，以電訊號進行脈衝調製，以BIBO和頻晶體進行1064nm 與1342nm 的和頻機制，達成短脈衝且高功率的橘黃光輸出，其脈寬為9.7奈秒，尖峰功率約為167瓦特。

關鍵字

布拉格繞射 ； 鈮酸鋰

並列摘要

Bragg condition is very sensitive to incident wavelength. With this characteristic, we can diffract wavelength with appropriate Bragg structure. In this letter, we first design an aperiodic structure with the help of simulated anneal algorism which compensates reciprocal vectors of dual wavelength emitted in Nd doped solid state laser system.
Lithium Niobate is a great electro-optic crystal. With the technics of high electric field poled, we can generate the structure we calculate previously on LN crystal. Thus, a 40 mm long, 5 mm in width and thickness of 0.5 mm aperiodic poled Lithium Niobate Bragg diffraction device is fabricated successfully.
In experiment, we measured the high diffraction efficiency both on 1064 nm and 1342 nm, 93.5% and 92.5% respectively, at 120 volt applied voltage. Furthermore, we put our chip into the Nd:YVO4 slid sate laser system and applied a periodic electric field to the chip, we can turn it into a cavity Q-switch device. With the sum frequency crystal BIBO, we can generate narrow and high peak power 593 nm output from dual emission wavelength of Nd 1064 nm and 1342 nm. In results, the yellow-orange light output with the pulse width of 9.7 ns and peak power of 167 W under 8.142 W of Nd absorption power.

並列關鍵字

Bragg Deflector ； Q-switch ； Lithium Niobate

參考文獻

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