Modulation Depth Based on Frequency-shift Characteristic of LiNbO3 Waveguide Electro-optic Intensity Modulator

The modulation depth,defined according to practical mod-ulation results,which changes with the microwave power and its fre-quency,is significant for systems utilizing the frequency-shift charac-teristic of the LiNbO3 waveguide Electro-Optic Intensity Modulator (EOIM).By analyzing the impedance mismatch between the micro-wave source and the EOIM,the effective voltage applied to the RF port of the EOIM is deprived frcm the microwave power and its fre-quency.Associating with analyses of the phase velocity mismatch be-tween the microwave and the optical wave,the theoretical modulation depth has been obtained,which is verified by experimental results.We provide a method to choose the appropriate modulation depth to optimize the desired sideband through proper transmission bias far the system based an the frequency-shift characteristic of the EOIM.     

近化学计量比LiNbO3晶体电畴结构观察和机理探讨

采用双坩埚提拉法(DCCZ)生长了各种不同成分的近化学计量比LiNbO₃晶体, 并用腐蚀法观察了其电畴结构. 结果表明, 化学成分对未经极化处理晶体的电畴结构起决定性作用, 当Li₂O 含量处于49.4mol%附近时, 晶体z面电畴呈现特殊的三次对称反畴; 当晶体中Li₂O含量为49.7mol%时, 晶体为完全单畴. 本文对其形成机理进行了探讨, 认为在由顺电相向铁电相转变 时, 局部铁电畴的极性方向与该处沿z轴方向的温度梯度正负密切相关, z轴生长晶体时, 由于相变发生所处位置离生长界面的距离受LiNbO₃晶体计量比影响, 所处温场固有温梯也 随之不同, 在此基础上解释了不同成分晶体的电畴结构形成原因. 最后讨论了控制铁电畴结构的工艺措施.     

LiNbO_3压电薄膜的研究进展

LiNbO3因其优异的压电性能和声表面波特性而被广泛应用于声表面波器件中。对LiNbO3的声表面波特性及薄膜制备技术进行了综述,并着重介绍了LiNbO3/蓝宝石及LiNbO3/金刚石多层结构的制备、声表面波特性的理论研究及压电薄膜研究进展。     

Influence of In3＋ ions concentration on spectroscopic properties of Ho：LiNbO3 crystals

In:Ho:LiNbO3 crystals doped with various concentrations of In3+(0, 1 mol.%, 3 mol.%, 5 mol.%), fixed concentrations of Ho3+ (1 mol.%) were grown by Czochralski method. The X-ray powder diffraction, infrared and UV-visible absorption spectra were measured and modified. Judd-Ofelt approach was employed to study the effect of In doping on spectroscopic properties of Ho:LiNbO3 crystals. In concentrations in crystals were analyzed by an inductively coupled plasma optical emission spectrometry (ICP-OE/MS). For In (3 mol.%):Ho (1 mol.%):LiNbO3 crystal, the obtained intensity parameters were: Ω2=9.6563, Ω4=4.2195, Ω6=14.1526. The results showed that the Ω2 and Ω6 parameters increased with the increase of In3+ concentration. When the In doping concentration was up to 5 mol.%, Ω2 and Ω6 suddenly decreased. In2O3 incorporation had a strong effect on the radiative lifetime, but had less influence on fluorescence branching ratios. The effective distribution coefficient of In3+ in In:Ho:LiNbO3 crystals was less than 1 and increased with increasing concentration of In3+ in the melt.     

Nd：MgO：LiNbO_3光波导的特性

用质子交换法制备了Ｎｄ：ＭｇＯ：ＬｉＮｂＯ３波导。通过测量平面波导的二次离子质谱，得到了波导的原子组分分布，并测量了Ｎｄ：ＭｇＯ：ＬｉＮｂＯ３晶体的吸收谱线，最后利用端面耦合，分别得到了条波导内和衬底内激光诱导的荧光谱线。     

高掺锌富锂铌酸锂体抗光损伤能力的研究

以Czochralski法生长Zn(6mol%)：LiNbO3,Li/Nb=0.94,0.97,1,1.02。测试晶体的光损伤阈值。采用质子交换法制作高掺锌富锂铌酸锂晶体光波导,研究了它们的抗光损伤能力。     

硅基LiNbO3薄膜的微结构研究

利用透射电子显微镜及X射线衍射，研究脉冲激光沉积技术(PLD)在Si(001)衬底上生长LiNbO3薄膜的微结构．结果表明，在600℃的衬底温度、30Pa的氧分压条件下，在硅片表面5nm厚的非晶氧化层上生长的薄膜，为c轴择优取向的单相LiNbO3晶体，本文还讨论了获得c轴择优取向LiNbO3薄膜的生长机理．     

Surface plasmon resonance triggered promising visible light photocatalysis of LiNbO3 ceramic supported Ag nanoparticles

LiNbO₃ ceramic was fabricated using solid-state reaction route. Silver nanoparticles (NPs) were loaded on LiNbO₃ at room temperature using silver nitrate and polyethylene glycol reagents, without the use of external heat and light energy. The X-ray diffraction showed only LiNbO₃ phase in Ag-loaded LiNbO₃ sample with no peak related to Ag metal due to small fraction of Ag loading. X-ray energy diffraction spectroscopy elemental color mapping confirmed the uniform loading of Ag metal on LiNbO₃ particles. Ag metal was loaded in the form of NPs as visualized under transmission electron microscope. Ag NPs-loaded LiNbO₃ showed enhanced absorption of visible light owing to the phenomenon of surface plasmon resonance (SPR). The loading of Ag NPs had no effect on the band gap energy of LiNbO₃ ceramic. X-ray photoelectron spectroscopy technique confirmed the metallic chemical state of Ag in Ag NPs-loaded LiNbO₃. Ag NPs-loaded LiNbO₃ degraded 97% rhodamine-B model dye from the solution when irradiated for 240 minutes under visible light. The dye degradation follows pseudo-first-order kinetic having k-value (kinetic rate constant) of as 0.013 min⁻¹. The ^•OH (hydroxyl) and (superoxide) radicals were the main active species behind the photocatalytic activity of Ag NPs-loaded LiNbO₃. Thus, Ag NPs-loaded LiNbO₃ could be a potential material for degrading organic dyes from water.     

胶合透镜法在LiNbO3：Fe晶体中制作光折变光子晶格

研究了一种制作光折变光子晶格的新方法——胶合透镜法。利用此方法在LiNbO3：Fe晶体中成功的制作了一维和二维光折变光子晶格。同时,对实验现象和实验原理进行分析得到,此种方法不仅可以得到较大面积的干涉区域从而可以制作出较大面积光折变光子晶格,此外这种方法可以实现晶格周期的连续调节,进而可以根据需求制作不同周期的光折变光子晶格。在实验中也验证了这种方法的优点与可行性,这对光子晶格的制作与研究有一定的意义。