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用干涉仪的方法测量了Ce:BaTiO3晶体的低频电光系数和压电系数.排除压电效应对光通过晶体引起相位的变化,得到低频下经极化的Ce:BaTiO3单晶的电光系数r42=1945±220pm/V和r13=11.8±1pm/V.从而,为研究Ce:BaTiO3晶体的光折变效应和理论计算提供了精确的线性电光系数
关键词: 相似文献
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通过理论模拟对具有上覆盖层的SiO2脊形条波导结构进行了优化,在此基础上利用微电子工艺制作了SiO2脊形波导Mach-Zehnder型电光调制器,并进行热极化引起的电光和非线性效应的研究.热极化过程大幅增强了样品的电光及非线性效应,二次电光系数由热极化前的1.56×10-22(m/V)2提高到热极化后的8.50×10-22(m/V)2,极化后得到了0.093pm/V的线性电光系数,对热极化的物理机理进行了理论分析.
关键词:
电光调制器
2光波导')" href="#">SiO2光波导
电光效应
热极化 相似文献
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研究了兼有电光效应和磁光效应的晶体内电光与磁光效应的互补特性及其传感应用. 在光强度调制条件下, 晶体中偏振光波的电光调制与磁光调制具有互相补偿的效果, 从而能够使输出光强度保持为一个固定值. 基于这种互补特性, 提出了一种利用单块闪烁锗酸铋(Bi4Ge3O12, BGO)晶体的电光补偿型光学电流(磁场)传感器, 其光学传感单元由两个偏振器和一块平行四边形BGO晶体组成. 该晶体自身能够产生π/2的光学相位偏置, 同时兼用作电流传感和电光补偿元件, 通过控制BGO晶体的外加电压, 能够实时补偿被测电流(磁场)变化引起的磁光旋转角和输出光强度的变化, 从而实现电流(磁场)的闭环光学测量. 实验测量了5.0 A范围内的工频交流电流, 所需要的电光补偿电压约为21.2 V/A, 补偿电压与被测电流之间具有良好的线性关系, 其非线性误差低于1.7%. 相似文献
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研究了晶场二级效应在PrF3晶体中的作用,发现该效应可使Pr3+离子的晶场单态与其他态混合,对PrF3晶体磁化率产生明显影响.进一步研究了晶体内的交换作用有效场,其形式为Hin=(1.9-0.02556T)×10-5M,在100—300 K的温度范围内,以此计算的PrF3晶体的倒数磁化率和Verdet常数的倒数与实验值符合较好.结果表明,在PrF3晶体中,晶场二级效应与离子间的交换作用都不能忽略.
关键词:
晶场二级效应
交换作用有效场
Verdet常数
3晶体')" href="#">PrF3晶体 相似文献
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许多光学现象如低强光下的电光效应、光弹效应,高强光下的光混频以及一些光散射效应,都在非线性光学之列.其中二阶非线性光学过程在非线性光学器件、远距离通讯和光混频中有着广泛的应用,因而研究十分活跃.但是,迄今多数研究限于无机绝缘体和半导体,因为人们对无机电介质的介电、压电、铁电性质,以及半导体中的输运现象的研究比较深入,对这些材料的性能比较熟悉. 七十年代以来,有机分子晶体和共轭聚合物晶体的非线性光学性质引起人们极大的兴趣.因为有机材料的二阶非线性光学系数极高(在许多情况下,比最好的无机晶体如KDP和LiNbO3高一个… 相似文献
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本文对钙钛矿型晶体的电光及倍频效应的机理提出了一个(MO6)离子基团模型。并从(TiO6)离子基团的准分子轨道及晶格场位能作用下的(TiO6)离子基团的离子键轨道出发,利用ABDP理论,分别计算了BaTiO3的各个电光及倍频系数。计算结果表明,在没有引入任何可调整参量的情况下,用(TiO6)离子基团的晶格场理论所得到的电光及倍频系数的计算值和实验值符合得相当好,而准分子轨道对这些效应的贡献很小。由 相似文献
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本文用文献[1]中所提出的(MO6)离子基团模型,计算LiNbO3,LiTaO3,KNbO3,BNN等晶体的电光和倍频系数。假设在Oh对称时,这些晶体中的氧八面体具有相同的能级和对称波函数,则通过群表示理论就可得到在C3ν,C2ν对称性时氧八面体的能级和对称波函数,并进而用ABDP理论计算它们的电光和倍频系数。计算结果和实验符合得相当好。本文并从理论上解释了这些晶体的倍频系数大小、符号和氧八面体畸变间的关系,由此可以得到以下两个结论:(1)畸变氧八面体的离子基团模型不但适用于钙钛矿型材料,同时也适用于钨青铜型、LiNbO3型材料。(2)在钨青铜型、LiNbO3型的材料中,仍是“离子键”对电光和倍频效应作出主要贡献,同时由于LiTaO3的共价键成份比LiNbO3大,因而LiTaO3的非线性光学效应比LiNbO3小。 相似文献
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Three oxide heterojunctions made of LaAlO3-δ/Si are fabricated under various oxygen pressures by laser molecular-beam epitaxy. They all show nonlinear and rectifying current--voltage characteristics, and the distinct difference in rectification behaviour among them. Their photoelectric properties are examined by a visible HeNe laser and an ultraviolet Hg lamp. We find that their photovoltaic responses are closely related to the oxygen contents in the LaAlO3-δ films. The junction fabricated under the lower oxygen pressure has a higher photovoltaic sensitivity. The possible mechanism is suggested based on the band structure of the p--n heterojunction. 相似文献
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Tatiana M. Petrova Alexander M. Solodov Alexander A. Solodov Vladimir M. Deichuli Vitalii I. Starikov 《Molecular physics》2018,116(23-24):3631-3641
ABSTRACTThe water vapour line broadening (γ) and shifting (δ) coefficients for 149 lines of 10 vibrational bands 2ν1, 2ν3, ν1?+?ν3, 2ν2?+?ν3, ν1?+?2ν2, ν2?+?2ν3, 2ν1?+?ν2, 3ν2?+?ν3, ν1?+?3ν2 and 6ν2 induced by hydrogen pressure were measured with a Bruker IFS 125 HR spectrometer. The measurements were performed at room temperature with a spectral resolution of 0.01 cm–1 and in a wide pressure range of H2. The calculations of the broadening coefficients γ and δ were performed in the framework of the semi-classical method using an effective vibrationally dependent interaction potential. The optimal sets of potential parameters that give the best agreement with the measured broadening coefficients for each vibrational band separately were found. Then combined experimental data of 16 vibrational bands of H2O perturbed by H2 were used to determine the analytical dependence of some potential parameters on vibrational quantum numbers. The analytical expressions that reproduce the broadening coefficients γ for different vibrational bands are proposed. 相似文献
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采用脉冲激光沉积技术,在单晶SrTiO3基底上外延生长了一系列名义结构为p×(NdBa2Cu3O7-δ(m)/YBa2Cu3O7-δ(n))的多层膜和准多层膜(单元层NdBa2Cu3O7-δ较厚而YBa2Cu3O7-δ呈非连贯的岛状分布,m,n为激光脉冲数,p为重复周期).样品的超导转变温度在87—91 K范围,具体大小取决于不同的调制结构,多层膜的重复周期越大,层状界面越多,超导转变温度就越低.磁传输测量表明,准多层的样品不仅具有较高的超导转变温度,而且具有较强的磁通钉扎性能,77K零场下的临界电流密度高达4×106 A/cm2,显示出良好的应用前景.
关键词:
2Cu3O7-δ')" href="#">NdBa2Cu3O7-δ
多层膜
磁通钉扎
临界电流密度 相似文献
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P. U. Sastry 《Pramana》2007,68(6):1001-1006
Linear electro-optical tensor coefficients and optical susceptibility of tetragonal KNbO3 are calculated using a formalism based on bond charge theory. Results are in close agreement with the experimental data.
The covalent Nb-O bonding network comprising the distorted NbO6 octahedral groups in the structure is found to be a major contributor to the electro-optic coefficients making these groups
more sensitive to these properties than the KO12 groups. The orientations of the chemical bonds play an important role in determining these properties.
相似文献
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P U Sastry 《Pramana》2002,59(3):547-552
Linear optical susceptibility and clamped linear electro-optical tensor coefficients of tetragonal BaTiO3 are calculated using a formalism based on bond charge theory. Calculated values are in close agreement with experimental
data. The covalent Ti-O bonds constituting distorted TiO6 octahedral groups are found to be major contributors to the electro-optic coefficients making them more sensitive than the
BaO12 groups for these properties. Orientations of chemical bonds play an important role in determining these properties. 相似文献
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Suleyman Cabuk 《Central European Journal of Physics》2012,10(1):239-252
The nonlinear optical properties of some ABO3 materials (BaTiO3, KNbO3, LiTaO3 and LiNbO3) are studied by density functional theory (DFT) in the local density approximation (LDA) expressions based on first-principle
calculations. Our goals are to give the details of the calculations for linear and nonlinear optical properties, including
the linear electro-optic (EO) tensor for some ABO3 structures with oxygen octahedral structures using first-principles methods. These results can then be used in the study
of the physics of ferroelectrics, specifically, we present calculations of the second harmonic generation response coefficient
X
ijk
(2) (−2ω, ω, ω) over a large frequency range for ABO3 crystals. The electronic linear EO susceptibility X
ijk
(2) (−ω, ω,0) is also evaluated below the band gap. These results are based on a series of the LDA calculations using DFT. Results for
X
ijk
(2) (−ω, ω,0) are in agreement with experiments below the band gap. The results are compared with the theoretical calculations and the
available experimental data. 相似文献
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The electro-optical properties of the PMN-xPT single-crystal relaxor solid solutions with different PT contents (x = 6, 10, 13%) and the PLMN-25PT transparent ceramic with a La content of 3%, which has been synthesized for the first time,
have been studied at room temperature. It has been shown that the dependence of the quadratic electro-optical coefficients
on the PT concentration in single crystals passes through a maximum at x ∼ 13%. It has been revealed that, although the PT concentration in the PLMN-25PT ceramic is above 13%, this material exhibits
the largest quadratic electro-optical coefficients and the lowest half-wave voltage among all the known relaxor systems. Possible
origins of the above phenomena have been discussed. 相似文献
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采用平面波赝势密度泛函理论研究了钛铝系金属间化合物TiAl3的结构性质, 计算值与实验值及其他理论值相符合. 通过准谐德拜模型研究了TiAl3的热动力学性质, 计算得到了相对体积(V/V0)与压强和温度的关系, 以及不同温度和压强下的热膨胀系数和热容. 与TiAl的计算结果进行对比, 发现随着温度的升高, TiAl的热膨胀系数增大的速度高于TiAl3, 且随着压强的增大温度效应减弱; TiAl3的热容值近似为TiAl的热容值的2倍.
关键词:
结构性质
热动力学性质
第一性原理
高压 相似文献