钒酸钇晶体折射率和折射率温度系数的测定

本文报道了钒酸钇(YVO4)晶体主折射率及其温度系数的测量,用自准直法在20～140℃温度范围内测量了这种晶体在488nm、632.8nm、1079.5nm和1341.4nm波长上的折射率,并得到了上述波长上的折射率温度系数和测量温度范围内修正的Sellmeier方程的常数,用得到的Sellmeier常数计算了1064nm波长下 YVO4晶体的双折射率(Δn),计算的Δn＝0.2082。结果与文献报道的值相当吻合。     

Er:SGB晶体主轴折射率测量

根据Er:Sr3Gd(BO3)3(Er:SGB)的透过率曲线粗略估计了该晶体的折射率,再利用自准直法,精确测量了30~170℃范围内,0.4880μm、0.6328μm、1.0640μm、1.338μm等波长下Er:SGB晶体的主轴折射率,得到Sellm e ier方程并计算了1.319μm下Er:SGB晶体的主轴折射率,与实验测量的结果进行比较,两者的差异不大于2×10-4,处在测量误差的范围内,验证了实验结果的可靠性。     

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.     

高抗灰迹KTP晶体的折射率测量与比较

利用改进的顶部籽晶熔盐法生长出高抗灰迹KTP晶体,使用自准直法测量了其在不同温度时若干波长下的主轴折射率,根据Sellmeier方程拟合出在测量波长区间内的主轴折射率色散曲线,计算出相应的倍频第Ⅱ类相位匹配方向,并与使用常规熔盐法生长的普通KTP晶体进行了比较.结果表明,高抗灰迹KTP的值始终比常规熔盐法生产的普通KTP大.     

吸收光谱测量晶体折射率的简易方法

折射率是晶体的基本参数,本文提出了利用透过光谱来测量晶体折射率的简易方法,此种方法具有对样品的尺寸要求低、测量范围无限制、操作简单、易获得一定光谱范围晶体折射率的优点.用吸收光谱法和自准直法测量了Nd:GGG的折射率,二者给出的折射率测量结果符合得很好,表明用晶体透射光谱来测量折射率是一种有效的简易测量方法.     

坩埚下降法生长La2Ti2O7晶体及其光性能研究

采用高温坩埚下降法生长La2 Ti2 O7晶体,获得的晶体尺寸约为18 mm× 12 mm× 10 mm,其表面出现了一系列(004)解理面.X射线双摇摆曲线表明该晶体具有良好的结晶质量.透过光谱显示退火后的La2 Ti2 O7晶体在可见光范围内是透明的,当波长在800 nm左右时,透过率将显著下降.La2 Ti2 O7晶体的吸收边出现在500 nm波长附近.光折射指数分析表明退火La2 Ti2 O7晶体具有高的折射率.折射率色散方程确定为n2(λ) =4.61643 +0.16198/(λ2-0.01547) -0.47201λ2,利用该公式可计算出300～1680 nm范围内任意波长下的折射指数n值.     

大尺寸CLBO单晶的生长和性质研究

本文对生长大尺寸硼酸铯锂(CsLiB6O10,简称CLBO)单晶的生长工艺进行了探索研究,采用顶部籽晶泡生法生长出尺寸为70×25mm的CLBO透明晶体.测量了晶体的干涉图,计算其折射率变化为Δn～1.2×10-5,晶体的光学质量接近于玻璃水平(～10-6).测量CLBO单晶的结构及其光学特性.用15mm×10mm×7mm的CLBO样品,在锁模Nd:YAG激光器上做倍频实验,获得了波长为532nm的倍频光,其转换效率高达60;以上.     

含孤立MO3平面基团晶体折射率计算

本文建立了一种计算含孤立MO3 (M=B,C)平面基团晶体折射率简单可行的方法,选择部分已知折射率的含孤立MO3平面基团的晶体,采用最小二乘拟合法,定出基团各向异性极化率和其晶体环境参数,并据此计算其它晶体的折射率.对30余种晶体折射率的计算结果表明,该方法所得结果与实测值之间相差不大于3.5;.同时计算了YCa4O(BO3)3,LaCa4O(BO3)3,Ca5(BO3)3F三种单斜晶体的折射率主轴方向,其中对LaCa4O(BO3)3和YCa4O(BO3)3两种晶体,计算结果与实验值符合很好,将为该晶体未来定向提供参考.     

铌酸钾锂晶体的生长和缺陷

用电阻加热提拉法生长了一系列较大尺寸,组分离子均匀性较好的铌酸钾锂晶体.利用X射线荧光光谱法测量了不同配比的熔体中生长出的晶体组成,用同步辐射X射线测量了晶体结构,结果表明随晶体组成变化,晶体的晶格常数发生了变化.根据晶体组分离子浓度与折射率的关系研究了晶体折射率变化情况,结果表明用本方法生长的大尺寸KLN晶体,寻常折射率no在测量误差范围内没有变化,非寻常折射率ne的变化率在820nm仅为1.22×10-4/mm,在410nm仅为1.93×10-4/mm.晶体的干涉条纹证明了晶体有良好的光学均匀性.结合晶体生长实验,探讨了改进晶体组分离子浓度分布均匀性的方法,结果表明采用籽晶和坩锅向相同方向旋转可以改善晶体生长界面处组分离子浓度的波动,提高晶体组分离子均匀性.晶体的缺陷研究表明晶体结构完整性较好,位错形状与晶体结构相一致,密度为7.5×104,[001]轴是晶体的极化轴.晶体对890～960nm波长范围的cw-Ti:sapphire激光倍频结果表明晶体有良好的倍频性能.     

椭圆偏振法研究B离子注入LiNbO_3光波导的光学特性

用椭圆偏振法研究了2.5 MeV B离子注入后的铌酸锂晶体,建立四层模型,对反射式椭圆偏振测量得出的数据进行反演拟合,得到了波导层厚度及0.3～0.8 μm波段波导层和损伤层的双折射色散曲线,发现低剂量B离子注入铌酸锂形成了折射率下降的位垒,在晶体表面下2.0 μm范围内得到了光波导结构.研究结果为以铌酸锂为基础的光波导器件研发提供了重要信息.     

Refractive index dispersion and anisotropy in Ca0.28Ba0.72Nb2O6

Room‐temperature refractive indices dispersion and anisotropy were measured in single Ca_0.28Ba_0.72Nb₂O₆ (CBN‐28) crystal between 380 and 700 nm. The refractive index of Ca_0.28Ba_0.72Nb₂O₆ are measured by the spectroscopic ellipsometry. The dispersion curves were fitted to different Sellemeier functions. The normal dispersions were observed. Using the interference of polarized light, the birefringence in the long wavelength region is obtained. The results are in good agreement with the reference. A new technique was used to analysis the experiment data and this technique is proved to be more simple and efficient. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Refractive index dispersion of spinel Zn2TiO4 single crystal

The transmittance and absorption spectra of a high‐quality Zn₂TiO₄ single crystal have been measured along the a‐axes at room‐temperature in the range of 200‐1000 nm. The wavelength dependent refractive index, extinction coefficient, real and imaginary parts of the complex dielectric constant of the Zn₂TiO₄ crystal have been derived from the measured T and α spectra. By fitting the refractive index spectrum, the Sellmeier dispersion equation of the Zn₂TiO₄ crystal has been obtained. The validity of Cauchy‐Sellmeier equation has been evaluated in the energy range of 2.90–3.20 eV representing the Urbach tail. Applying the single‐effective oscillator model, the dispersion energy E_d and the oscillator energy E₀ have been determined as 18.76 and 5.05 eV, respectively. The obtained dispersion energy E_d takes on ionic crystal value. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Refractive index,band gap and oscillator parameters of amorphous GaSe thin films

GaSe thin films are obtained by evaporating GaSe crystals onto ultrasonically cleaned glass substrates kept at room temperature under a pressure of ∼10^–5 Torr. The X‐ray analysis revealed that these films are of amorphous nature. The reflectance and transmittance of the films are measured in the incident photon energy range of 1.1–3.0 eV. The absorption coefficient spectral analysis revealed the existence of long and wide band tails of the localized states in the low absorption region. The band tails width is calculated to be 0.42 eV. The analysis of the absorption coefficient in the high absorption region revealed an indirect forbidden band gap of 1.93 eV. The transmittance analysis in the incidence photon wavelength range of 500–1100 nm allowed the determination of refractive index as function of wave length. The refractive index–wavelength variation leads to the determination of dispersion and oscillator energies as 31.23 and 3.90 eV, respectively. The static refractive index and static dielectric constant were also calculated as a result of the later data and found to be 9.0 and 3.0, respectively. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

位错对BBO晶体光学均匀性的影响

本文报道了BBO晶体中位错密度对光学均匀性的影响.样品的光学均匀性是利用Wyko RTI 4100型干涉仪进行测量.采用侵蚀法观测BBO晶体{001}面的位错密度,在一定的侵蚀条件下,观察到BBO晶体{001}面上的位错露头为突起的正三方锥形,底边与X轴平行.在显微镜下测量出样品的蚀坑密度.实验证明,随着位错密度的增加BBO晶体的光学均匀性逐渐变差.     

Refractive index dispersion of relaxor ferroelectric 0.9Pb(Zn1/3Nb2/3)O3‐0.1PbTiO3 single crystal

The refractive indices of 0.9Pb(Zn_1/3Nb_2/3)O₃‐0.1PbTiO₃ single crystal at different wavelengths have been measured by the minimum deviation method at room temperature, and their dispersion equations are obtained. The parameters connected to the energy band structure are obtained by fitting single‐oscillator dispersion equation. Despersion energies are found to take on covalent crystal values. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Order Parameter and Refractive Index of Cholesteryl Linoleate

Refractive indices of cholesteryl linoleate are determined at different temperatures and order parameters have been calculated in smectic and cholesteric phases.