KTP晶体的水热法生长及其光学性能的测量

使用水热法成功生长出大尺寸、高质量的KTP晶体,对该晶体的光学性能进行测量分析.由LambDA900分光光度计测量得到的水热法生长KTP晶体的透过率曲线表明晶体具有良好的光透过性能,其透过短波下限与熔盐法生长的KTP晶体基本相当.利用自准直法精确测量水热法生长KTP晶体的折射率,拟合得到30℃下折射率的Sellmeier方程的系数,并计算532nm与1319nm波长对应的主轴折射率,计算值与实验值相吻合.     

抗"灰迹"KTP晶体光学性能研究

用改进的熔盐顶部籽晶法生长了KTiOPO4(KTP)晶体并对该晶体进行了抗"灰迹"性能测试.测试表明,在功率密度为120kW/cm2的1064nm激光和10kW/cm2的532nm激光共同照射1000s后, 晶体在633nm处的吸收依然维持在1.05×10-4/cm左右,表明该晶体比普通KTP晶体具有更高的抗 "灰迹"性能.透过率测试表明,用本方法生长的KTP晶体在波长短于500nm的区域比普通KTP晶体有更高的透过率.通过实验测定,得出该晶体在室温下1064nm倍频Ⅱ类相位匹配角θ=90°时φ=24.40°.     

Ga3+:KTP晶体c向电导率的研究

采用ICP-AES法测定了Ga3+:KTP晶体中掺质Ga3+离子含量,并由此得出Ga3+离子在相应晶体生长体系中的平均分配系数为0.0373;采用静电计和多频测试仪测定并计算出Ga3+:KTP晶体c向的电导率,将其与纯KTP晶体者进行比较.结果发现,Ga3+:KTP晶体c向电导率比纯KTP晶体c向电导率在交流情况下最大降低了两个数量级以上.文中对晶体c向电导率的降低机理进行了探讨.     

熔盐法和水热法KTP晶体的晶胞参数及拉曼光谱特征

利用X射线衍射和显微激光拉曼光谱研究熔盐法自发结晶的KTP晶体、顶部籽晶熔盐法KTP晶体和水热法KTP晶体的晶胞参数和拉曼光谱特征,分析和比较不同方法生长的KTP晶体的晶体结构与化学键特征峰.研究表明:KTP晶体的晶胞参数与晶体生长方法有关,熔盐法自发结晶的KTP晶体生长过程中降温速率较快,晶胞体积相对较小;熔盐法和水热法KTP晶体中部分拉曼特征峰的位置因生长方法不同呈现一定的差异,水热法KTP晶体在782 cm-1、744 cm-1和515 cm-1处出现的特征峰可视为水热法KTP晶体的标志峰,借此可将其与熔盐法晶体相区分.     

Nb∶KTiOPO4晶体的生长和倍频性能

通过研究晶体生长工艺参数对Nb∶KTiOPO4(Nb∶KTP)晶体生长的影响,用熔盐顶部籽晶法获得尺寸为55mm×25mm×5mm的Nb∶KTP透明单晶.研究中发现熔体的温度梯度、籽晶和降温速率将严重影响Nb∶KTP晶体的生长.Nb离子的引入不利于Nb∶KTP晶体的生长,尤其是造成晶体易开裂,且沿a轴方向生长速度非常缓慢.同时,Nb的引入大大改变Nb∶KTP晶体的倍频性能.掺杂Nb浓度的摩尔分数为13;时,Nb∶KTP晶体的倍频的Ⅱ型相位匹配的截止波长缩短至937nm,且有效产生469nm倍频蓝光;掺杂Nb浓度的摩尔分数为3;时,Nb∶KTP晶体对Nd∶YAG的1.0642μm激光倍频的最佳相位匹配角为θ=88.32°,()=0°,非常接近90°非临界相位匹配方向.     

Nb：KTiOPO4晶体的生长和倍频性能

通过研究晶体生长工艺参数对Nb∶KTiOPO4(Nb∶KTP)晶体生长的影响,用熔盐顶部籽晶法获得尺寸为55mm×25mm×5mm的Nb∶KTP透明单晶.研究中发现熔体的温度梯度、籽晶和降温速率将严重影响Nb∶KTP晶体的生长.Nb离子的引入不利于Nb∶KTP晶体的生长,尤其是造成晶体易开裂,且沿a轴方向生长速度非常缓慢.同时,Nb的引入大大改变Nb∶KTP晶体的倍频性能.掺杂Nb浓度的摩尔分数为13%时,Nb∶KTP晶体的倍频的Ⅱ型相位匹配的截止波长缩短至937nm,且有效产生469nm倍频蓝光;掺杂Nb浓度的摩尔分数为3%时,Nb∶KTP晶体对Nd∶YAG的1.0642μm激光倍频的最佳相位匹配角为θ=88.32°,()=0°,非常接近90°非临界相位匹配方向.     

单掺Rb+和Cs+的KTP晶体生长及其电导率

采用高温溶液降温法在掺质浓度均为5mol;的KTP-K4溶液中分别生长了单掺Rb+和Cs+的KTP晶体,发现掺质改变了晶体生长习性,在相应生长体系中掺质Rb+和Cs+的分配系数分别为O.646和0.08,掺质KTP晶体的晶胞参数a0和b0比纯KTP晶体者略有增长.通过掺Rb+或Cs+,KTP晶体的c向电导率明显降低,但晶体在350～1100nm范围内的光透过性质未受影响.     

掺质KTP型晶体生长与性能研究

采用高温溶液法生长了含掺质离子Zr4+,Ga3+的单掺和双掺系列KTP型晶体.晶体生长过程中发现Ga掺入溶液后,体系更加稳定,容易生长出光学质量的晶体;而Zr掺入溶液后体系稳定性降低,晶体生长较困难.用等离子体发射光谱测定了各掺质离子在晶体中的含量,计算出掺质离子的分配系数,发现生长体系中Ga无论是在高掺入量还是低掺入量的情况下,Ga在晶体中的含量都十分稳定.测定了晶体的晶胞参数、紫外-可见-红外吸收光谱,测定的结果发现,晶胞参数均变化不大,在吸收光谱中Ga:KTP在可见光谱区有少量的光吸收,而Zr:KTP晶体是无色透明的.通过粉末倍频实验发现,Zr的掺入有助于晶体倍频转换效率的提高.通过晶体c轴向离子电导率的测试发现,Ga的掺入使c轴向电导率降低了大约3个数量级.双掺Zr和Ga的晶体是性能更为优良的掺质KTP型晶体.     

KTP晶体的电光研究进展

本文简述了KTP晶体的电光性能并与KD*P、LN晶体进行了比较。概括了KTP晶体电光器件研究的主要进展。对水热法生长的KTP晶体和熔剂法生长的KTP晶体在电光应用中的优缺点进行了分析。最后介绍了熔剂法生长的低电导率KTP晶体在电光领域的应用研究。     

掺杂对磷酸钛氧钾单晶拉曼光谱的影响

本文研究了掺金属元素Ce和Nb的磷酸钛氧钾(KTiOPO4,简称KTP)晶体在不同几何配置下的拉曼光散射.讨论了掺杂对KTP拉曼光谱的影响.拉曼光谱大的散射强度说明晶体有大的非线性光学特性.从掺铈和掺铌KTP中氧八面体和氧四面体相对于KTP的频率位移可知,稀土金属离子Ce比Nb离子对KTP拉曼光谱的影响更大.     

介电超晶格结构极化设备的研究

针对介电超晶格结构的特殊极化问题,自行研制了极化设备.研究了Windows操作系统下实现高频精确定时的高性能定时器法.基于此方法实现了极化设备的任意波形发生器及信号采集功能.研制开发了高精度0～10 kV稳压电源,产生满足要求的极化电压.利用这种设备完成了化学计量比钽酸锂晶体的极化实验.结果表明设备运行稳定可靠,性能良好.     

外加电场法制备周期极化铌酸锂的重要结构参数的数值分析

外加电场法制备周期极化铌酸锂工艺的众多结构参数对极化进程有潜在的影响.本文采用数值方法系统的分析了周期极化的重要结构参数的影响,这些参数包括绝缘层介电常数、绝缘层厚度、电极宽度、外加电压幅度和光栅周期.证明了对极化进程影响最为显著的是电极宽度、外加电压幅度和光栅周期,它们应该是设计极化结构时需要考虑的主要参数.相对的,绝缘层介电常数、绝缘层厚度对极化进程的影响在一定条件下可以忽略.本文由此推论了一种简洁合理的极化结构设计步骤.另外,本文得到了光栅周期与最优电极宽度的二次拟合公式,它为设计提供了依据,降低了复杂程度.     

The DC Conductive Property of KTiOPO4 Crystal along its Z-Axis

The anomalous DC electrical conductive property of the KTP crystal along its z-axis is reported in this paper. The DC conductivity strongly depends on the measuring voltage. No Ohmic regime exists in the current-voltage relation. Ionic polarization occurs under high DC stresses. Electrode reactions were also observed. The phenomena are related to the easy movement of ions along the z-axis of the KTP crystal.     

水热法KTP晶体生长与宏观缺陷研究

本文报道了水热法KTP晶体的生长工艺及晶体生长形态,系统研究了水热法KTP晶体的宏观缺陷,其宏观缺陷主要为添晶、生长脊线、裂隙和包裹体.提出了晶体生长工艺的改进措施,如提高原材料和试剂的纯度、调整籽晶的悬挂方式、减少籽晶的尺寸等,都可以减少晶体的宏观缺陷,提高晶体的质量.//(011)切向的籽晶生长的晶体质量较高,且能很好地应用于激光器件中.     

A survey of research on KTP and its analogue crystals

This paper reviews the growth and properties of KTiOPOP₄ (KTP) and its analogue crystals including its isomorphous crystals and doped crystals. Based on the calculation of the refractive indices and phase matching of KTP crystals, it is shown that non-critical phase matching can be achieved theoretically. In a 4%Nb-doped KTP crystal, non-critical phase matching was obtained with a pulsed Nd:YAG laser in an efficiency of ca. 4%. Most of the isomorphous and doped KTP crystals possess similar physical, optical and nonlinear optical properties as those of KTP.RbTiOPO₄, KTiOASO₄ and RbTiOASO₄ crystals have better electrooptical figure of merit and RbTiOPO₄ crystals have a fast ion conductor character. Some doped KTP crystals have shown high second harmonic generation efficiencies and damage thresholds. But the homogeneity of KTP analogue crystals is poorer than that of KTP. On the base of damage threshold tests using a CW Argon laser, it is concluded that the best second harmonic generation crystal among all the KTP analogue crystals is still KTP itself. Special care must be taken to eliminate impurity centers to avoid the formation of gray track and photorefractive centers.     

Second harmonic generation optimization in thermally poled borophosphate glasses and characterization by XANES and XPS

Second harmonic generation (SHG) in poled glasses opens new opportunities in material research and device development for optics. SHG results that relate to thermally poled new borophosphate glasses have been analyzed. By a cycling poling–depoling process an optimization of the SHG response can be obtained. As the signal is localized near the surfaces in contact with the electrodes during poling, XPS and X-ray absorption near-edge spectroscopy (XANES) spectroscopies have been performed to characterize cathodic and anodic surfaces of these glasses before poling, and after poling or depoling treatments. Structural differences are observed by XANES at the O K-edge after poling on both surfaces. Moreover, an accumulation of Na⁺ mobile cations is evidenced on the cathodic surface by XPS spectroscopy confirming the migration of Na⁺ mobile cations after the glass has been submitted to high dc field. Finally, the XPS and XANES investigations of poled glasses evidences some breakage of phosphate chains in the glass network which occur during the poling treatment. Conversely, bridging bonds are partly restored after thermal depoling.     

Dynamic photorefractivity guided by single-pulse voltage

The dynamic photorefractivity in a cell with photoconducting orienting layers, filled with a nematic liquid crystal (LC) 6CHBT and a mixture of anthraquinone dyes AD1 and AD2, has been investigated. The single-pulse mode, in which the polarity and amplitude of a dc electric field applied to an LC cell are switched for a fixed time interval, has been used. The scheme of dynamic self-diffraction of low-power laser beams was used in the experiment. The dependences of the width and intensity of diffraction pulses on the bias and switching voltages have been investigated. It is established that the width and intensity of the diffraction pulse arising after initial voltage recovery depends also on the switching pulse width. At the optimal width of the control pulse, the diffraction efficiency increases by two orders of magnitude.