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1、随机电磁光束的传输特性原创性声明原创性声明 本人声明兹呈交的学位论文是本人在导师指导下完成的研究成果。论文写作中不包含其他人已经发表或撰写过的研究内容，如参考他人或集体的科研成果，均在论文中以明确的方式说明。本人依法享有和承担由此论文所产生的权利和责任。 学位论文作者签名： 日期： 学位论文版权使用授权声明学位论文版权使用授权声明 本人同意授权华侨大学有权保留并向国家机关或机构送交学位论文和磁盘，允许学位论文被查阅和借阅。 论文作者签名： 指导教师签名： 签 名 日 期： 签 名 日 期： II华侨大学硕士学位论文论文摘要论文摘要Nd：YVO4晶体以其吸收系数大，发射截面大，输出线偏振等优点备
2、受大家的关注。Nd：YVO4激光器输出的 1342 nm 激光波长接近人眼安全区，以及石英光纤的低色散和低损耗区, 所以在激光医学、光纤通信、光纤传感定位和中红外参量振荡器的抽运源等领域有广泛的应用前景；其倍频的 671 nm 红光对应着彩色全息感光胶层的最大光谱灵敏度，而且可作为 Cr：LiSAF 等其它激光器的抽运光源。此外，采用 KTP、LBO 等非线性晶体对 LD 抽运的 Nd：YVO4激光器输出的 1342 nm 和 1064 nm 激光进行和频，可以得到 593 nm 黄色激光。在 1342 nm 激光输出的较高功率 LD 端面连续抽运 Nd：YVO4激光器的实验研究中，比较了不同
3、腔长和不同输入镜曲率半径下的激光输出功率，最大斜率效率约为 22%。结果表明，小功率抽运时，激光器的输出功率基本随抽运功率线性增加；当抽运功率超过一定值时，斜率效率下降，对于长腔斜率效率下降更为明显，甚至出现输出功率降低。通过对晶体中的激光基模半径和热致衍射损耗的计算得出：高抽运功率下，热效应影响了激光器的输出功率，为了获得最大的激光转换效率，激光晶体内不考虑热效应时的基模半径与抽运激光光束尺寸的比值0 / p 在 0.80.9 之间最佳，而且抽运功率越大，比值越小。理论分析与实验结果基本一致。在 LD 端面连续抽运的 Nd：YVO4 / KTP 折叠腔腔内倍频激光器的实验研究中，比较了不同腔
4、型结构的红光输出功率，并在实验中获得折叠镜的最佳折叠角度为 25，其有效倍频效率为 10.8 %。从理论上对三镜折叠腔结构进行优化设计，研究了腔长、输入镜曲率半径和Nd：YVO4、KTP 晶体的热效应对激光谐振腔的稳定区域和 Nd：YVO41华侨大学硕士学位论文晶体内激光基模光斑半径的影响；并首次引入研究腔内倍频偏振状态改变的 Jones 矩阵法来分析折叠角度对输出功率的影响，得到最适合的折叠角度，实验结果与理论吻合。从而进一步完善了折叠腔结构的激光器研究。采用简单平凹腔结构实现 Nd：YVO4 / KTP 腔内和频输出 593 nm黄光。理论上比较了 KTP 和 LBO 和频的相位匹配条件，
5、在输出镜对1342 nm 激光的反射率为 99.7 %时，由双波长振荡条件获得输出镜对1064 nm 激光的最佳透射率约为 97.3。在此基础上，当抽运功率为9.1W 时，两种激光在谐振腔内的光功率分支比为 1.26，从而实现激光运转的增益匹配，获得最大的和频输出。理论与实验基本吻合。关键词：关键词：LD 抽运 Nd：YVO4激光器；1342 nm 激光；KTP 腔内倍频；Jones 矩阵法；和频2华侨大学硕士学位论文ABSTRACTNd：YVO4 crystal is famous for its excellencies of high absorptioncross-section、hi
6、gh emission cross-section and polarizing output laser.Due to the 1342nm laser obtained by Nd：YVO4 laser is near the areas ofeye safety and low loss and disperse of optical fiber, it has extensiveapplication in laser medical, fiber communication, fiber Sensingpositioning and mid infrared optical para
7、metric oscillator. 671nm redlaser which is its frequency-doubled laser is corresponding the highestspectrum sensitivity of Color Holography photographic glue layer, so itcan be used to be pump source of the other laser such as Cr：LiSAF laser.On the side, with nonlinear crystal such as KTP and LBO, 5
8、93 nm YellowLaser generates simultaneous laser action at wavelength 1064 nm and1342 nm produced by laser-diode-pumped Nd：YVO4 laser.Comparison of the output power in different cavity length and differentcurvature radius of input mirror, the highest slope efficiency was about22% in laser-diode end-pu
9、mped Nd：YVO4 laser at 1342nm. It was seenthat when the pump power was low, the output power increased linearlynearly; when it exceeded a certain range, the slope efficiency decreased,especially for the longer cavity in which output power descended withpump power increasing. Then TEM00 mode size in c
10、rystal and thermalinduced diffraction losses was calculated in theory. The results showedthat Thermal effect had influence on the output power of laser, TEM00mode size in crystal without thermal effect to pump beam size / pwas preferable between 0.8 and 0.9 at high pump powers to gain largeroutput p
11、ower and the ratio would be less with the larger pump power. Theexperimental results agreed with theoretical predict.Output power of laser-diode end-pumped Nd：YVO4 / KTP frequency-3华侨大学硕士学位论文doubled Laser was studied at different cavity structure. The red laser wasobtained with effective frequency-d
12、oubled efficiency 10.8% in theoptimal folded angle 25. The 3-mirror folded resonator was optimizedby the research about influence of parameters including the resonatorlength, curvature radii of mirrors, NdYVO4 and KTP thermal effect onthe resonator stability and basic mode size of NdYVO4 crystal. Th
13、eoptimum folded angle was obtained by the Jones matrix method whichwas first used to analyze the effect of folded angle on the output power.This work made the theory of folded Resonator laser perfect further.The research was about 593nm yellow laser obtained by Nd：YVO4 /KTP intracavity sum-frequency
14、 mixing in plane-concave cavity. Phasematching condition of sum-frequency crystals KTP and LBO wascompared in theory. Based on the conditions of multiwavelengthoscillation criterion, the result was that when the reflectivity of inputmirror to 1342nm was 99.7%, the reflectivity of it to 1064nm was 97
15、.3%.In this precondition, when the input power was 9.1W, the ratio ofintracavity power of two wavelength laser was 1.26. The theory coincidesessentially with the experiment.Key words：Laser-diode -pumped Nd:YVO4 laser；1342nm laser；KTPintracavity frequency doubling；Jones matrix method；Sum-frequency4（华
16、侨大学硕士学位论文第一章第一章概述概述自六十年代激光器问世以后，固体激光器迅速发展起来。七十年代到八十年代传统的灯泵固体激光器的低效率和热效应等问题，使其研究和应用受到了一定的限制。八十年代中后期，激光二极管（LD）性能的迅速提高使得全固态激光器表现出效率高、稳定性好、寿命长等优点。与传统的灯泵固体激光器相比： 1）总体效率可达到 30%-70%，提高 510 倍，LD 窄的发射光谱线宽与激光介质的吸收峰对应，使光能更多地用来增加反转粒子数； 2）更高的频率稳定性和更窄的线宽，热效应减小，冷却要求降低，无很大的机械噪声，LD 输出功率稳定性提高；（3）可靠性高，使用寿命大大延长，可达 104-105 小时；（4）小型化，外形尺寸缩小 80%-90%，体积小，重量轻，供能简便。这些优点使其在激光成像、激光空间对接、激光制导、水下通信、精密加工、集成电路修复、激光医学等领域得到广泛应用。目前它的研究已成为激光学
