摘要
小型的藍光和綠光固態雷射對於雷射全彩顯示(laser display)扮演著重要角色，因此本論文將研究雷射二極體激發摻雜釹的硼酸鈣釔晶體(Nd:YCOB)晶體的綠光雷射與藍光材料GaN的基板LSAT晶體。
摻雜釹的硼酸鈣釔晶體(Nd:YCOB)是新興的自倍頻晶體材料，他同時具有雷射作用(lasing)與倍頻轉換的功能，使得雷射共振腔的設計簡化，由於YCOB晶體屬同成分熔融(congruent melting)化合物，因此可以使用傳統熔化提拉法(Czochralski method)生長出高光學品質及化學性質穩定的晶體，也降低了生產成本。摻雜釹的硼酸鈣釔晶體有自倍頻出紅綠藍三種可見光的潛力，預期未來將有機會廣泛的應用在光電產品上，其中以綠光雷射的效率最好，有文獻報告達6.2%的轉換效率。本論文推導了自倍頻晶體的雜訊模型，並且實際的完成光路的設計，利用最大輸出功率1W的雷射二極體(laser diode)激發摻雜13%釹的硼酸鈣釔晶體(Nd:YCOB)，我們量測到自倍頻輸出綠光約0.87mW此時激發光源的功率約477mW，驅動電流約1.05安培，轉換效率約0.18%。；接著利用Fabry-Perot干涉儀(interferometers)來掃描其縱向模態數，發現共振腔為多模(multi- longitudinal mode)操作，為了解決綠色雜訊問題，我們希望達成雷射共振腔單模操作的機制。我們嘗試了兩種方法來改善，第一種方法為加強晶體散熱，另一種方法為couple cavity 的方式。
藍光材料GaN的基板晶體LSAT[(La,Sr)(Al,Ta)O3]晶體是一種混合的鈣鈦礦形式(perovskite-type) 晶體，它有很好的特性當作氮化鎵(gallium nitride)晶體的基板，因為LSAT晶體與氮化鎵(gallium nitride)有較小的晶格不匹配(lattice mismatch)約0.06%~1.00%，然而在波長450nm處，有吸收的缺陷(defect)，我們利用退火(annealing)的方法來除去缺陷。我們可以觀察到退火前LSAT晶體呈現紅棕色，退火後則呈現淡黃色。

Abstract
The Nd:YCOB crystal is a new self-frequency doubling (SFD) crystal. The self-frequency doubling scheme is appealing because it simplifies the laser cavity by synthesizing both good laser performance and harmonic generation property into a single optical element, which means easier assembling and lower cost. By self-frequency doubling (SFD) method, the Nd:YCOB crystal has a great potential to produce green,red and blue lasers.
In this thesis, we derived the theoretical noise model of the Nd:YCOB crystal. A few simulation results were demonstrated. We also obtained 0.87mW cw green output with less than 1W diode pump power focused in the 13% Nd:YOCB crystal. Subsequently, we measured the number of the longitudinal modes by the Fabry-Perot interferometers. There were multi-longitudinal modes in the laser cavity. In order to suppress the green noise, single longitudinal mode operation was preferred. Therefore, we try two methods to solve problems. We improved the cooling of the Nd:YCOB crystal, and added an output coupler after the laser cavity. However, single mode operation has not yet been not achieved.
LSAT[(La,Sr)(Al,Ta)O3] crystal is a new candidate single crystal as a substrate for gallium nitride epitaxial growth. Excellent lattice matching with gallium nitride makes this material specially promising. However, small absorption observed in as-grown crystal close to 450nm seems to be connected with the existence of colour centres. Annealing removes these defects.

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