双轴晶体KTiOPO_4的多频率变换

由相位匹配条件计算了KTiOPO_4晶体的多频率变换的参数,讨论了偏振特性、走离效应以及转换效率。计算了KTP的参量振荡条件。     

KTiOPO_4双轴晶体最佳相位匹配参数的计算

本文给出了可能的相位匹配角和实验结果。除了进行一系列计算外,还推导了双轴晶体的有效非线性系数表达式,并分别计算了KTPⅠ类和Ⅱ类倍频非线性系数的数值。因此决定了最佳的相位匹配方向,并计算出了离散角的理论值、失谐的影响、临界晶体长度。这些结果为双轴晶体的最佳工作在理论和实践上都提供了指导。     

KTiOPO_4晶体的喇曼光谱研究

本文报道了优质非线性晶体KT_iOPO_4的喇曼光谱,在各种几何配置下获得了它的各类模,计算了它们的相对强度,讨论了结构与光谱的关系.     

KTiOPO_4晶体中Cr离子的光谱特性

通过实验测得ＫＴｉＯＰＯ４：Ｃｒ晶体的室温吸收谱、激发谱，室温和液氮温度下激光诱导荧光谱及各发射带的荧光寿命，进而计算得到了Ｃｒ离子的晶场参数、吸收截面、发射截面及量子效率。结果表明Ｃｒ离子受晶场的影响较弱，但具有较强的电子－声子耦合。室温下较大的无辐射跃迁几率导致了较低的量子效率。实验上没有观察到四配位Ｃｒ离子的光谱特征。最后，对上述结果结合Ｃｒ离子配位情况进行了讨论。     

Hilbert-Huang变换的自适应频率多分辨分析研究

Hilbert-Huang变换方法能自适应地提取非平稳数据的局部均值曲线,将复杂的叠加信号分解成有限数量的、且有物理意义的内蕴模式分量函数,从而得到有意义的瞬时频率和希尔伯特时频谱.它是一种局域波分析方法.其特点是比小波分析有更高的时频分辨率,没有Wigner-Ville分布的交叉项,特别适合分析非平稳数据.本文根据Hilbert-Huang变换的原理,推导出内蕴模式函数的递推表达式,给出了希尔伯特谱的最高频率分辨率,首次提出了一种新的的自适应频率多分辨分析原理和方法,从而完善了局域波分析的理论.     

双轴晶体的双折射

本文就光入射到双轴晶体的情况给出有关求折射方向的一般方法。按云母的相应数据画出三视图，使晶体转动时折射光的轨迹明显可见。当入射面和晶面是晶体的主介电轴平面和光为正入射时，给出折射光线方向的公式。它们提供了测量晶片光学常数的一种方法。此外，还讨论了对应于一入射线的两折射光E矢量之间的夹角。     

双轴晶体的双折射

本文就光入射到双轴晶体的情况给出有关求折射光方向的一般方法。按云母的相应数据画出三视图,使晶体转动时折射光的轨迹明显可见。当入射面和晶面是晶体的主介电轴平面和光为正入射时,给出折射光线方向的公式。它们提供了测量晶片光学常数的一种方法。此外,还讨论了对应于一入射线的两折射光E矢量之间的夹角。     

电压频率变换比为10,000:1的多谐振荡器

在一般的非稳态多谐振荡器上简单地附加一电路,可使其频率范围和占空因数得到很大的改善。此外,这种非稳态电路极易变为单稳工作,并能保持原来的工作特性。共有两种电路,其基本电路很简单。控制电压V_C决定电容充电时间,因此可以获得很宽的频率范围。另一比较复杂的电路是自启动电路,它作为自激多谐振荡器使用,并外加了元件以改善输出豚冲波形。其元件如图所示,控制电压在V_(CC)至2伏之间,工作频率为1赫至12千赫。基本电路的频率上限取决于电流源的最大值和定     

微波集成电路频率变换装置

用于频率变换的微波集成电路包含一对混频器,它们把接收的输入射频信号与一对正交频率调制信号棍合,然后通过正交耦合器将混频器的输出合成,抑制除了输入射频信号和频率调制信号之外的其它所有信号。在强冲击、温度变化显著并且要求稳定性高、工作迅捷的环境中,通过最大程度地减小微波集成电路体积来达到上述要求,此微波集成电路陶磁基片的上下两个表面均有微带线。混频器由4个二极管组成,它们被压焊至微带的一个表面,以便承受较大的冲力。利用相对面上锥形地平面保证适当的平衡。抑制下边带的正交耦合器是兰杰(LANGE)形耦合器,它被集成在基片的上表面。     

压力传感器的频率输出变换

引言典型的半导体压力传感器变换所加的压力为一“低电平”电压信号，现在的技术能在单片硅集成电路（ＩＣ）上使传感器的输出温度补偿和放大到较高的电压电平。在芯片上温度补偿和信号调节提供一有效的增加量值到基本的读出器件时，必须考虑如何使最后的输出和接口做进一...     

SHG and internal conical refraction experiments in CsTiOAsO4, comparison with KTiOPO4 and KTiOAsO4, for1.32-μm type II SHG

The internal conical refraction angles between 0.5321.32 μm, the phase-matching directions of 1.064 μm type I second harmonic generation (SHG) and of 1.32-μm type II SHG are measured in a sphere of CsTiOAsO₄ (CTA). The relative sign and absolute magnitude of two independent quadratic nonlinear coefficients are determined by 1.32-μm phase-matched type II SHG conversion efficiency measurements in a sphere and strips: d₁₅=1.09±0.09 pm/V and d₂₄=1.7±0.6 pm/V at 0.65 μm. AH the results are compared with previous work. The comparison of CTA with KTiOPO₄ and KTiOAsO₄ is made in order to evaluate the crystal which provides the highest conversion efficiency for 1.32-μm type II SHG depending on the crystal length and on the beam waist radius     

Singlemode channel waveguides and electrooptic modulators in KTiOPO4 for the short visible wavelength region

Single-mode channel waveguides at short visible wavelengths have been fabricated in KTiOPO₄ by Rb&rlhar2;K ion exchange in mixed melts of RbNO₃-KNO₃-Ba(NO₃)₂ . The technological parameters have been chosen by means of theoretical WKB- and “effective index” calculations concerning the singlemode region of the effective channel waveguide index N₀₀ at the given wavelength. Great diffusion anisotropy and small dispersion of the surface refractive index change guarantee singlemode operation of the very same channel waveguide from the blue up to the red. Typical attenuation of about 2.0 dB/cm for TM- and 1.5 dB/cm for TE polarization was obtained at λ=0.5145 μm. Light-induced refractive index changes (photorefractive effect) have been determined as a function of time, wavelength, guided optical mode intensity and temperature. The light-induced effects in Rb&rlhar2;K ion-exchanged channel waveguides in KTiOPO₄ are about two orders of magnitude smaller than those in annealed proton-exchanged channel waveguides in LiNbO₃. Electrooptic phase modulators have been successfully investigated concerning dynamic V_π measurements, the electric-optical field overlap and dc-drift phenomena. Design, fabrication and experimental results of integrated-optic Mach-Zehnder-interferometer modulators for short visible wavelengths are presented     

Second harmonic generation and sum frequency mixing of dualwavelength Nd:YAlO3 laser in flux grown KTiOPO4crystal

On the basis of accurately measured refractive indexes, the authors have obtained the Sellmeier's equations for flux grown KTiOPO ₄ (KTP) crystal and used them to calculate the phase matched angles (&thetas;_m, φ_m) and effective nonlinear coefficients (d_eff) for type I and III second harmonic generation (SHG) and sum frequency mixing (SFM) of radiations at 1.0795 and 1.3414 μm. The optimum phase matching conditions for 1.0795 and 1.3414 μm SHG are that &thetas;_m=86.88 and 58.88°, respectively, in an XZ plane (φ=0) and for SMF of 1.0795 and 1.3414 μm in the same plane 76.02°. The corresponding d_eff values calculated from &thetas; _ms are 18.07×10^-9 and 17.42×10^-9 esu     

激光晶体Y3Ga5O12:Cr3+的MS-Xα计算

本文报道了具有D3d格位对称性的过渡金属络合离子团[CrO6]9-的自旋非限制MS-Xα计算结果.给出了单电子本征值与本征函数.讨论了激光晶体Y3Ga5O12:Cr3+的电子结构.用Slater过渡态方法计算了晶场分裂参数10Dq及晶场低对称畸变引起的电子能级分裂值及一些反映局域电子结构的参数.计算结果与实验符合较好.     

引上法生长可调谐激光晶体BeAl_2O_4:Cr~(3+)

掺铬铝酸铍晶体作为可调谐激光晶体,在近几年来颇受国内外重视。这种晶体激光器能室温运转,可调谐范围宽,结构简单,输出功率高。目前在民用或军事应用上已开始应用,有可能会有更广泛的应用。我们的工作表明,铬酸铍晶体生长的研究中主要存在着防毒、铝酸铍相形成动力学以及熔体老化等特殊问题。 (1)我们在配料过程中,为防铍尘毒害,改革了操作设备、工艺条件,使配料间内的空气中铍含量降至0.5微克/米~3,符合国家劳保条例的要求。 (2)由于我们配料条件不同,铝酸铍相形成条件与粉末混匀料不同。实验表明,铝酸铍相     

基于BGO晶体的磁光式冲击电流传感器及其信号处理

本文提出了一种基于偏振检测原理,采用Bi₄Ge ₃O₁₂(BGO)晶体的磁光式冲击电流传感器,可以测 量幅值范围10 kA到90 kA的8/20 μs冲击电流。由于冲击电流的持续时间极短,光源功率漂移对测量的干 扰可以忽略,偏振检测结构可以保证测量结果的正确性。由于BGO晶体具有维尔德常数大的 突出优点,传 感器可以获得较高的测量灵敏度。利用小波分解法,并以信噪比(SNR)和平滑度(SR) 作为去噪结果的 评价标准,确定了合适的小波函数(Daubechies Db7)和分解层数(5层),有效地去除了 测量结果中的干 扰噪声。此电流传感器的灵敏度达到0.262°/ kA,具有较好的线性度,且冲击电流幅值的测量误差控制在 ±5%以内。本文所提出的电流传感器具有结构简单、性能可靠的优点,适用于雷电流测试、 核物理实验和高功率脉冲激光研究等恶劣环境下的冲击电流测量。     

Improved second-harmonic generation by selective Yb ion doping in anew nonlinear optical crystal YCa4O(BO3)3

We describe experiments characterizing a new nonlinear optical crystal, YCa₄O(BO₃)₃ (YCOB). This crystal has a number of advantages over other commonly available nonlinear optical crystals. It has a higher nonlinear coefficient than KDP, can be fabricated to large sizes (~3-in diameter, 8-in length), and has a high damage threshold. Moreover, this new nonlinear optical crystal is nonhygroscopic, has good optical quality and mechanical properties, allowing easy optical polishing. This crystal, YCa₄ O(BO₃)₃, commonly termed YCOB, is one of a family of new nonlinear crystals, the oxyborates, that include RECa₄O(BO₃)₃ (RE=La³⁺, La ³⁺, Y³⁺, Sm³⁺, Gd³⁺, Er³⁺, and Nd³⁺). In this paper, we also successfully demonstrate a technique for improving the nonlinear optical properties of this crystal. This technique, ion substitution, has previously had limited success with other crystal hosts. However, the inclusion of yttrium in YCOB provides the opportunity to exploit this technique. Yb³⁺, which has larger mass, but approximately the same atomic size as Y³⁺ can be substituted into the crystal structure without introducing stress and nonuniformities. A systematic investigation of the linear and nonlinear characteristics of several crystals doped with various levels of Yb demonstrate that selective substitution of Yb in YCa₄O(BO₃)₃ improves the second-harmonic conversion efficiency by increasing the optical nonlinearity     

He~＋离子注入KTiOPO_4晶体波导的制备及其性能研究

报道了液氮温度Ｈｅ＋离子不同的注入能量和剂量条件下ＫＴｉＯＰＯ４晶体波导的制备，利用Ｍ线光谱法测量了退火后波导各导模的有效折射率，计算了波导层折射率的分布和晶体中离子的射程分布与损伤分布，二者吻合得较好。     

BaGa4Se7与KTiOAsO4光参量振荡产生中红外激光性能对比

BaGa₄Se₇(硒镓钡,简称BGSe)与KTiOAsO₄(砷酸氧钛钾,简称KTA)均可在1.06 μm激光泵浦下产生中红外激光。首先仿真计算出两种非线性晶体的相位匹配曲线,结果显示:切割角为(56.3°, 0°)的BGSe晶体在I类相位匹配条件下和切割角为(90°, 0°)的KTA在II-A类相位匹配条件下均可产生~3.5 μm的闲频光。然后理论计算出BGSe (56.3°, 0°, I类)的有效非线性系数为?11.9 pm/V,KTA(90°, 0°,II-A类)的有效非线性系数为?3.2 pm/V;在其他条件相同的情况下,15 mm长BGSe (56.3°, 0°, I类) 的OPO振荡阈值是20 mm长KTA (90°, 0°, II-A类) OPO振荡阈值的35.11%。最后通过实验验证BGSe (56.3°, 0°, I类, 15 mm) 的振荡阈值小于KTA(90°, 0°, II-A类, 20 mm),输出的中红外激光能量大于KTA。因此,BGSe是一种极具应用前景的中红外非线性晶体。