周期极化LiNbO3晶体中电极布置对反转畴扩张的影响

利用外加电场极化的方法,分别研究了三种不同方式布置的极化电极对C向切割LiNbO_{3< /sub>晶体极化反转畴扩张的影响.实验结果表明在相同极化条件下，当极化电极长度方向与六边 形反转畴一对边呈90°和0°角时，极化扩张速度分别为0.089μm/ms和0.011μm/ms.实验结果揭示，为了有效地控制极化占空比，在制备一维准相位匹配LiNbO3晶体时应 避免极化电极与六边形反转畴壁中一对边呈90°的情况. 关键词： 周期极化 极化扩张 准相位匹配}     

周期极化晶体单谐振参量振荡随机偏差分析

研究了周期极化晶体的随机边界偏差对准相位匹配（QPM）单谐振参量振荡器（SROs）的增益以及振荡阈值的影响,提出了一种处理该问题的合理的近似方法,推导出了QPM-SROs增益和阈值与随机偏差比率的关系式,推得的公式与已经发表的经验公式吻合。分析结果表明：随机周期长度偏差对QPM-SROs的增益和阈值的影响要远比同样大小的随机占空比偏差来得大;QPM-SROs的增益与反转畴个数的平方成正比,阈值与之成反比。     

高功率中红外3.8 μm激光器

 采用1.06 μm激光泵浦准相位匹配周期极化铌酸锂（PPMgLN）晶体光参量振荡器,实现高功率高效率高重复频率3.84 μm中红外激光输出。泵浦源为椭圆光斑1.06 μm激光,PPMgLN晶体MgO摩尔分数为5%,光参量振荡器为外腔单谐振结构,采用e→e+e相位匹配,利用了PPMgLN晶体的最大非线性系数。在1.06 μm激光功率为73 W,声光Q开关工作频率为7.5 kHz的条件下,获得平均功率8.3 W,波长3.84 μm激光输出,光-光转换斜率效率14.1％,水平和垂直方向光束质量平方因子分别为1.94,4.57。     

Compact efficient optical parametric generator internal to a Q-switched Nd:YVO4 laser with periodically poled MgO:LiNbO3

This paper demonstrates a compact efficient optical parametric generator internal to a Q-switched diode-end-pumped Nd:YVOquasi-phase-matching, intracavity optical parametric generator, periodically poled MgO-doped lithium niobate (PPMgLN)Project supported by the National Natural Science Foundation of China (Grant Nos 10474071 and 60671036).4265K, 4260F, 4270This paper demonstrates a compact efficient optical parametric generator internal to a Q-switched diode-end-pumped Nd:YVOquasi-phase-matching, intracavity optical parametric generator, periodically poled MgO-doped lithium niobate (PPMgLN)Project supported by the National Natural Science Foundation of China (Grant Nos 10474071 and 60671036).4265K, 4260F, 4270This paper demonstrates a compact efficient optical parametric generator internal to a Q-switched diode-end-pumped Nd:YVOquasi-phase-matching, intracavity optical parametric generator, periodically poled MgO-doped lithium niobate (PPMgLN)Project supported by the National Natural Science Foundation of China (Grant Nos 10474071 and 60671036).4265K, 4260F, 4270This paper demonstrates a compact efficient optical parametric generator internal to a Q-switched diode-end-pumped Nd:YVOquasi-phase-matching, intracavity optical parametric generator, periodically poled MgO-doped lithium niobate (PPMgLN)Project supported by the National Natural Science Foundation of China (Grant Nos 10474071 and 60671036).4265K, 4260F, 4270This paper demonstrates a compact efficient optical parametric generator internal to a Q-switched diode-end-pumped Nd:YVOquasi-phase-matching, intracavity optical parametric generator, periodically poled MgO-doped lithium niobate (PPMgLN)Project supported by the National Natural Science Foundation of China (Grant Nos 10474071 and 60671036).4265K, 4260F, 4270This paper demonstrates a compact efficient optical parametric generator internal to a Q-switched diode-end-pumped Nd:YVO$_{4}$ laser with periodically poled MgO:LiNbO₃(PPMgLN). With the Q-switch set at a repetition rate of 25kHz and the PPMgLN crystal operated at room temperature (25\du\,), the intracavity optical parametric generator threshold was reached as a diode pump power of 0.9\,W. A maximum signal output power of 0.34W with a pulse width of 25\,ns and a beam quality factor of 1.4 was obtained at an incident diode power of 3.4\,W, leading to a conversion efficiency of 10{\%} with a slope efficiency of 14.4{\%}. By varying the crystal temperature from 25 to 200\du, the output signal wavelengths were tuned in range of 1506--1565\,nm. Over a 30-minutes interval, the instability of the signal power was measured to be less than 1{\%}. In addition, the threshold pump intensity for the intracavity optical parametric generator is theoretically investigated, and the obtained result is in good agreement with the experimental results.     

低阈值宽调谐的内腔调QNd∶YVO_4/PPLN光学参量产生

将多周期极化铌酸锂(PPLN)晶体置于激光二极管(LD)端面抽运的声光调QNd∶YVO4激光器谐振腔内,实现了准相位匹配内腔光学参量直接产生(QPM-IOPG)。PPLN晶体长20 mm,利用外加电场极化法制作,极化沿晶体的z向进行。设定声光Q开关重复频率为19 kHz,通过温度调谐和周期调谐,获得了信号光在1384~1541 nm范围内的连续输出,脉冲宽度约为80 ns。在PPLN晶体温度为140℃,极化周期为29μm时,内腔光参量产生的阈值仅为0.93 W,在3 W激光二极管抽运功率下,获得了140 mW的信号光输出;在极化周期为26.5μm时,内腔光参量产生的阈值增大到1.36 W,在3 W激光二极管抽运功率下,获得了105 mW的信号光输出。分析了不同极化周期下阈值和转换效率存在差异的原因,对内腔光学参量产生的阈值进行了理论分析和计算。     

Dielectric superlattices for nonlinear optical effects

Dielectric superlattices show a lot of new phenomena that are promising in applications, such as nonlinear optical frequency conversion and optical bistability. This paper reviews the main achievements in this field. Much has been focused on the work done in our Lab. Since 1980, we have extended the concept of superlattice from semiconductor to dielectrics. When quasi-phase-matching technique is introduced into a quasiperiodic dielectric superlattice, more interesting phenomena can occur. For example, multiwavelength second-harmonic generation and coupled parametric processes such as direct third-harmonic generation have been realized with high efficiency. A new mechanism for optical bistability in a 2-dimensional dielectric superlattice, i.e. a 2-dimensional nonlinear photonic crystal, has been proposed theoretically had proved experimentally.     

准相位匹配（QPM）技术研究新进展

准相位匹配是一种人为地制备周期结构以实现非线性频率转换技术,它拓宽了非线性晶体应用范围,提高了频率转换效率。本文详细介绍了准相位匹配主要技术优势,并描述周期极化畴反转技术,这一当前普遍用来制备准相位匹配非线性晶体的实验方法,同时总结了这一领域国内外研究的最新进展。     

啁啾型周期性调制晶体中感应非线性群速度色散的研究

提出了一种研究啁啾型周期极性铌酸锂晶体 (CPPLN)中非线性群速度色散的简单方法。发现不仅谐波可以获得色散 ,而且在一定条件下基频光也可以在CPPLN中获得色散。讨论了CPPLN的色散特性 ,并与传统色散元件进行了比较。     

1064nm泵浦掺氧化镁周期极化铌酸锂晶体(PPMgLN)光学参量产生器的研究

本文利用二极管泵浦的声光调Q Nd:YAG激光器输出的1064nm准连续激光为泵浦源,利用掺氧化镁周期极化铌酸锂晶体(PPMgLN)为工作物质,实现了温度调谐准相位匹配参量光的输出。输出参量光功率稳定,调谐范围宽。当晶体温度从40℃到180℃变化时,输出信号光的波长调谐范围为1.567-1.673μm,相应的空闲光的调谐范围为2.923-3.315μm。当输入1064nm平均功率为1.017W时,输出信号光功率为185mW,相应的空闲光功率为106mW,总功率为291mW。     

差频产生中红外光源的大气痕量成分高灵敏检测系统研究

室温工作的连续可调谐相干光源在痕量气体检测技术中有着重要应用价值,非线性差频产生方法是获得室温工作的中红外相干光源的有效途径,是对传统激光光源的重要补充.研究了基于准相位匹配技术的差频产生基本原理和PPLN晶体的温度调谐特性;以甲醛为检测目标气体,研究了基于差频产生的大气甲醛中红外高灵敏探测系统组成,采用光通信波段半导体激光器和掺镱光纤激光器作为信号和泵浦激光,通过PPLN晶体的非线性差频过程实现3.53 μm差频输出.系统具有室温工作、全光纤耦合、结构紧凑的特点,能够满足大气痕量气体实时在线检测的需要.