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361.
We present a method for improving the dispersion tolerance of a dual-arm Mach-Zehnder modulator by independently optimizing the applied voltage on each arm and the time delay between them. We found a significant improvement in the dispersion tolerance. Using the negative chirp effect and the time delay, it was possible to extend the transmission distance of 10 Gbit/s optical nonreturn-to-zero signals without any additional electrical or optical components. 相似文献
362.
铌酸锂、钽酸锂晶体的结构特征 总被引:1,自引:1,他引:1
从铌酸锂和钽酸锂晶体的结晶学数据出发,分析其结构特征和组成化学键的结合情况.对于这两个晶体的结晶学格位占有情况和阳离子的位移进行了理论上的分析.作者首次明确地给出了铌酸锂和钽酸锂晶体中与晶体组成有关的阳离子位移趋势. 相似文献
363.
Contributions on the Thermal Behaviour of Oxoniobates of the Transition Metals. IV The Chemical Vapour Transport of CoNb2O6 with Cl2, NH4Cl, or HgCl2. Experiments and Calculations Well shaped crystals of CoNb2O6 were obtained by CVT using Cl2 (added as PtCl2), NH4Cl or HgCl2 as transport agents (1020°C → 960°C). As a result of thermodynamic calculations the evaporation and deposition of CoNb2O6 in the presence of Cl2 can be expressed by the heterogenous endothermic equilibrium (1). The endothermic reaction (2) is responsible for the CVT of CoNb2O6 if NH4Cl is used as transport agent: The unfavourable site of the equilibrium (3) causes the small transport effect using HgCl2 as transport agent. Assuming ΔBH°298(CoNb2O6,s) = ?524.7 kcal/mol a satisfying agreement between thermodynamical calculation and experimental results can be reached. 相似文献
364.
The high-temperature polymorphs of two photocatalytic materials, BiNbO4 and BiTaO4 were synthesized by the ceramic method. The crystal structures of these materials were determined by single-crystal X-ray diffraction. BiNbO4 and BiTaO4 crystallize into the triclinic system P1¯ (No. 2), with a=5.5376(4) Å, b=7.6184(3) Å, c=7.9324(36) Å, α=102.565(3)°, β=90.143(2)°, γ=92.788 (4)°, V=326.21 (5) Å3, Z=4 and a=5.931 (1) Å, b=7.672 (2) Å, c=7.786 (2) Å, α=102.94 (3)°, β=90.04 (3)° γ=93.53 (3)°, V=344.59 (1) Å3 and Z=4, respectively. The structures along the c-axis, consist of layers of [Bi2O2] units separated by puckered sheets of (Nb/Ta)O6 octahedra. Photocatalytic studies on the degradation of dyes indicate selectivity of BiNbO4 towards aromatics containing quinonic and azo functional groups. 相似文献
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368.
Highly c-axis oriented aluminum nitride (AlN) films were deposited on z-cut LiNbO3 substrates by reactive rf magnetron sputtering. The crystalline properties investigated by X-ray diffraction (XRD) revealed that AlN film with (0 0 2) preferred orientation was improved by an increase of the deposition time within the experimental range. However, the surface morphology of AlN film measured by scanning probe microscopy (SPM) showed that the roughness was getting worse with increase of deposition time. Surface acoustic wave (SAW) properties, measured by a network analyzer in the structure consisting of highly c-axis AlN films on z-cut LiNbO3 substrates, were investigated. The phase velocity (VP) was significantly increased by the increase of h/λ, where h is the thickness of AlN film and λ is the wavelength. However, the insertion loss (IL) of SAW filters was also increased by the increase of h/λ. Experimental results on the temperature characteristics of SAW devices are also presented. 相似文献
369.
Grating spacing dependence of nonvolatile holographic recording in doubly doped lithium niobate crystals is theoretically investigated allowing arbitrary charge transport lengths. It is shown that the nonvolatile refractive index modulation initially increases with increasing grating spacing, then a saturation behavior arises because of the dominant bulk photovoltaic effect. Although different charge transport length results in different nonvolatile refractive index modulation, the grating spacing dependence of nonvolatile holographic recording obeys almost the same rules for arbitrary charge transport lengths. The experimental results obtained by recording nonvolatile holograms in LiNbO3:Cu:Ce crystals with different grating spacing are consistent with the theoretical analyses. 相似文献
370.