LYB晶体主轴折射率测量与评价

采用自准直法测量了在30℃~170℃范围内,0.473 μm、0.632 8 μm、1.064 0 μm、1.338 μm等波长下LYB晶体的主轴折射率,得到Sellmeier方程并计算了1.319 μm下该晶体的主轴折射率,与实验测量的结果进行了比较,两者之间的吻合性较好.测量结果表明,该晶体具有较低的折射率以及折射率随温度变化小,热稳定性较好.     

自准直法测GdTaO4晶体折射率

本文利用自准直法在473, 532, 632.8和1064 nm的激光波长上精确地测量出GdTaO₄晶体的折射率, 得到了Sellmeier方程, 并计算了在632 nm处光轴与折射率主轴n_z的夹角为21.75°, 进而得知GdTaO₄晶体是正光性双轴晶体.     

测量晶体最大双折射率温度系数的偏光干涉法

介绍了测量晶体的最大双折射率温度系数的偏光干涉法. 利用分光光度计测量出不同温度下晶体波片的偏光干涉谱. 通过对不同温度下谱线极值点所对应波长的精确判断,准确计算出相应的最大双折射率,并由曲线拟合得到最大双折射率温度系数的表达式. 测量的双折射率精度可达到10-5.     

红外光学材料折射率温度系数测量装置

本文介绍一台红外光学材料折射率温度系数测量装置。该装置是由温控系统、精密测角系统、光学系统和电器控制系统等组成的一台高精度全自动化测量系统，采用改进的自准直法测量折射率温度系数值。该装置达到的主要技术指标：工作波长为2～12μm，温度范围为-50～150℃，测量不确定度为3%，可满足各种红外光学材料折射率温度系数测量的要求。利用该装置对红外材料锗折射率温度系数值进行了测量，并对测量数据进行了报道。     

Nd^3＋：YAlO3晶体折射率温度系数的表示式

建立了Nd~(3+):YAlO_3(Nd:YAP)晶体折射率温度系数的表示式,该式得到的结果与测量值间具有较好的一致性。利用这个式子可以计算0.5398μm～1.0795μm波长范围311K～455K温度范围内Nd:YAP晶体的折射率温度系数。     

高掺镁铌酸钾晶体的主折射率及其温度系数的测量

本文报道掺5mol%MgO的铌酸锂(liNbO_3)晶体的主折射率n_o、n_o及其温度系数.用自准直法在0.5398μm、0.6328μm、1.0795μm和1.3414μm波长上,并在20℃～160℃温度范周内,测量了该晶体的主折射率,并获得在这些波长上的折射率温度系数.修正的Sellmeier方程的常数也在20℃～160℃温度内推算出.用此结果计算室温的二次谐波I类临界相位匹配角与实验值符合得很好,又计算二次谐波的非临界相位匹配温度,其结果也与实验值较符合.     

KIO3晶体折射率和倍频系数的测量

首次测量了无孪无畴的KIO_3晶体的主折射率和倍频系数.     

高掺镁LiNbO3晶体折射率温度系数的表示式

推导了掺５ｍｏｌ％ＭｇＯ的ＬｉＮｂＯ３晶体折射率温度系数的表示式。利用这些表示式可以计算２９３～４２８Ｋ温度和０．５３９８μｍ～１．３４１４μｍ波长范围内的折射率温度系度，结果表明：计算值和实验值的最大相对偏差是１２％，用具有最大相对偏差的折射率温度系数的计算值，计算１．０７９５μｍ波长的非临界相位匹配温度，其值为３８２．４Ｋ，它与实验值仅差６Ｋ。因此，本文得到的表示式，对于采用这种晶体，设计在上     

改性KTP晶体主折射率及主折射率温度系数的测量

报道了用自准直法在０．５３９８μｍ、１．０７９５μｍ和１．３４１４μｍ激光波长上测量了摩尔比为０．０７５的Ｎｂ：ＫＴｉＯＰＯ４晶体的主折射率及其温度系数,得到了该晶体的塞耳迈耶尔方程,用此结果计算了该晶体对１．０７９５μｍＮｓｄ：ＹＡｌＯ３激光倍频的Ⅱ类最佳相位匹配角,计算结果与累进发符合。     

石英晶体的色散方程及折射率温度系数

研究了石英晶体在不同温度下折射率随波长的变化规律.通过对Sellmeier方程严格求解,得出了其系数表达式,计算出了不同波长对应的折射率,经验证与实验值符合得很好.通过曲线拟合求解出了折射率温度系数表达式,由此式可计算出不同波长折射率温度系数;进一步求解出了Sellmeier方程常量随温度变化地数值,得到求解不同温度任意波长的石英晶体主折射率的一种方法.     

Refractive indices of SrTiO3 in the infrared region

We measured transmittance and reflectance spectra of SrTiO₃ crystals in the infrared region, at 200 and 100 K. These data and our previous 300 and 20 K data are analyzed in order to derive frequency and temperature dependence of the refractive indices n and k. We thus provide detailed n(v) and k(v) data at 300, 200, 100, and 20 K, in the frequency range 25–16000 cm⁻¹.     

Improvement of Atomic-Layer-Deposited Al2O3/GaAs Interface Property by Sulfuration and NH3 Thermal Nitridation

Fermi level pinning at the interface between high-h gate dielectric and GaAs induced by unstable native oxides is a major obstacle for high performance GaAs-based metal-oxide-semiconductor （MOS） devices. We demonstrate the improved Al2O3/GaAs interracial characteristics by （NH4）2S immersion and NH3 thermal pretreatment prior to A1203 deposition. X-ray photoelectron spectroscopy （XPS） analysis confirms that sulfuration of GaAs surface by （NH4 ）2S solution can effectively reduce As-O bonds while Ga-O bonds and elemental As still exist at Al2O3 /GaAs interface. However, it is found that N incorporation during the further thermal nitridation on sulfurated GaAs can effectively suppress the native oxides and elemental As in the sequent deposition of Al2O3. Atomic force microscopy （AFM） shows that the further thermal nitridation on sulfurated GaAs surface can also improve the surface roughness.     

Properties of a New Nonlinear Optical Crystal CdZn2B2O6

Cadmium dizinc diborate （CdZn2B2O6） single crystals have been grown for the first time. The crystal structure of CdZn2B2O6 is the same as that of the Cd3Zn3B4O12. The x-ray diffraction, infrared and Raman spectra, differential scanning calorimetry analysis and density indicate that the physical and chemical properties of both crystals are very similar. Especially, the nonlinear optical coefficients of CdZn2B2O6 and Cd3Zn3B4O12 crystals are 2.6 and 2.4 times as large as that of KH2PO4 crystal respectively. Chemical etching experiments indicated that these crystals are very stable in neutral solution and not hygroscopic in air at room temperature.     

Photoluminescence Property of Co3O4 Nanowires

Co3O4 nanowire arrays are fabricated by electrodeposition with following heat-treatment in atmosphere ambient. Photoluminescence is investigated at 295K. In the experiment, when increasing the excitation light wavelength from 260 nm to 360 nm, two kinds of emissions corresponding to the increasing excitation light wavelength are observed. One of them alters the excited emission position, another keeps its emission position. The distinct behaviour of excited emissions related to the increasing excitation wavelength indicates that the mechanism of them must be different. According to the experimental comparison and first-principle calculation, the two kinds of emissions are discussed.     

The properties of the Y2O3 films exposed at elevated temperature

Yttrium trioxide (Y₂O₃) thin films have been deposited on silicon (1 1 1) substrates by RF magnetron sputtering. The influences of thermal exposure at high temperature in air on the structure, the surface morphology, roughness, and the refractive index of the Y₂O₃ thin film were investigated by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), atomic force microscopy (AFM), and spectroscopic ellipsometry (SE). The results indicate that chemical composition of the as-deposited Y₂O₃ film is apparently close to the stoichiometric ratio, and it has a cubic polycrystalline structure but the crystallinity is poor. The monoclinic and cubic phases can coexist in the Y₂O₃ film after thermal exposure to 900 °C, and the monoclinic phase disappears completely after 300 s exposure to 950 °C. The changes of the surface morphology, roughness, and the refractive index of the Y₂O₃ film are closely related to the crystal structure, the internal stress, and various defects influenced by thermal exposure temperature and time.     

Influences of Bi2O3/V2O5 Additives on the Microstructure and Magnetic Properties of Lithium Ferrite

Lithium ferrite materials with different concentrations of Bi2O3 and V2O5 additives are prepared by the conventional ceramic technique. The x-ray diffraction analysis proves that the additives do not affect the final crystal phase of the lithium ferrite in our testing range. Both Bi2O3 and V2O5 additives could promote densification and lower sintering temperature of the lithium ferrite. The average grain size first increases, and then gradually decreases with the Bi2O3 content. The maximal grain size appears with 0.25 wt% Bi2O3. The average grain size first increases, and then is kept almost unchanged with the V2O5 content. The maximal average grain size of the samples with V2O5 additive is much smaller than that of the samples with Bi2O3 additive. Furthermore, the V2O5 additive more easily enters the crystal lattice of the lithium ferrite than the Bi2O3 additive. These characteristics evidently affect the magnetic properties, such as saturation flux density, ratio of remanence Br to saturation flux density Bs, and coercive force of the lithium ferrite. The mechanisms involved are discussed.