不同Li／NbZr：Fe：LiNbO3晶体的生长及光折变效应的研究

采用Czochralski技术生长不同Li/Nb双掺杂Zr:Fe:LiNbO3晶体,测试了晶体的光学均匀性和抗光折变能力.Zr:Fe:LiNbO3晶体双折射梯度比Fe:LiNbO3晶体降低一个数量级,抗光折变能力比Fe:LiNbO3晶体提高一个数量级,发现Zr4 在LiNbO3中具有抗光折变能力.采用二波耦合光路测试不同Li/Nb的Zr:Fe:LiNbO3晶体的衍射效率、响应时间、擦除时间并计算了动态范围和灵敏度,Zr:Fe:LiNbO3晶体的响应速度,灵敏度和动态范围都比Fe:LiNbO3晶体高,它的全息存储性能优于Fe:LiNbO3晶体.     

不同Li/Nb比Mg:In:Fe:LiNbO3晶体的光折变性能研究

采用提拉法生长了不同Li/Nb比(Li/Nb=0.85,0.94,1.05,1.20,1.38)的Mg:In:Fe:LiNbO3(LN)单晶.测试了Mg:In:Fe:LN晶体的红外透射光谱,紫外吸收光谱,抗光致散射能力,响应时间和指数增益系数.实验结果显示:Li/Nb=0.85晶体的OH-吸收峰在3481cm-1附近, Li/Nb=0.94、1.05、1.20的晶体的OH-吸收峰在3505cm-1附近,而Li/Nb=1.38晶体的OH-吸收峰有三个,分别在3466cm-1、3481cm-1和3518cm-1附近.随着Li/Nb比的增大,晶体的紫外吸收边发生紫移,抗光致散射能力增强,响应速度加快,指数增益系数增大.结果表明:Li/Nb=1.38的晶体是性能最为优良的光折变晶体材料.     

Zn∶Mn∶Fe∶LiNbO_3晶体的非挥发性存储

以Czochralski技术生长不同Li/Nb比Zn∶Mn∶Fe∶LiNbO3晶体。测试晶体抗光散射能力,Li/Nb=1.38的Zn∶Mn∶Fe∶LiNbO3晶体抗光散射能力比Fe∶LiNbO3高一个数量级以上。以二波耦合光路,双波长(蓝光-红光)存储技术,测试晶体全息存储性能,结果表明双波长存储性能优于双色存储。双波长(蓝光-红光)(476nm)的光激载流子是空穴。Mn离子是浅能级,Fe离子是深能级。采用Li/Nb=0.94和1.05的Zn∶Mn∶Fe∶LiNbO3晶体作为存储介质,以双波长(蓝光-红光)进行非挥发存储实验,它的非挥发衍射效率和响应速度高于双色存储。     

双掺杂铌酸锂晶体的生长及其光折变性质

采用提拉法以固液同成分配比(Li2CO3/Nb2O5＝48.6/51.4)生长了Fe掺杂及(Zn,Fe)、(Mg,Fe)和(Ce,Fe)双掺杂LiNbO3(LN)单晶.Ce:Fe:LiNbO3晶体的质量,指数增益系数和衍射效率皆高于Fe:LiNbO3晶体.所测得(Zn,Fe):LN、(Ce,Fe):LN、(Mg,Fe):LN和Fe:LiNbO3晶体的抗光致散射能力分别为8.2×103,3.2×102,8.3×102和1.2×102W/cm3;在488nm光进行的光折变实验中还原处理后的(Ce,Fe):LiNbO3晶体具有最高的二波耦合增益系数,为40.2cm-1,其全息衍射效率可达82.2%;实验结果表明(Zn,Fe):LiNbO3和(Mg,Fe):LiNbO3具有抗光散射能力强,响应时间短的特点,而(Ce,Fe):LiNbO3的增益系数和衍射效率均为最高,明显优于Fe:LiNbO3晶体.     

In:Er:LiNbO3晶体生长及光损伤性能研究

在LiNbO3晶体中掺入In2O3和Er2O3,利用提拉法生长了In:Er:LiNbO3晶体,获得了In和Er在晶体中的分凝系数.通过测试晶体的吸收光谱和抗光损伤能力,确定In:Er:LiNbO3晶体中In的掺杂阈值浓度为～3mol;,In(3mol;):Er:LiNbO3晶体的抗光损伤能力比Er:LiNbO3提高3个数量级以上.研究了In的掺入使Er:LiNbO3晶体的吸收边移动和抗光损伤能力提高的机理.     

Sc:In:Fe:LiNbO3晶体的生长及全息关联存储的研究

在Fe:LiNbO3中掺进Sc2O3和In2O3采用Czochralski技术生长Sc:In:Fe:LiNbO3晶体.测试Sc:In:Fe:LiNbO3晶体的红外光谱和抗光致散射能力.Sc(1mol;):In(2mol;):Fe:LiNbO3晶体OH-吸收峰移到3508cm-1,抗光致散射能力比Fe:LiNbO3晶体提高二个数量级.对Sc(1mol;):In(2mol;):Fe:LiNbO3晶体OH-吸收峰移动机理和抗光致散射能力增强的机理进行讨论.以Sc(1mol;):In(2mol;):Fe:LiNbO3晶体作存储元件,以Cu:KNSBN晶体作为位相共轭镜进行全息关联存储,试验结果表明全息关联存储的成象质量高、图象清晰完整、噪音小.     

Sc:Fe:LiNbO3晶体的生长和光学性能研究

研究双掺Fe(0.03wt;Fe2O3)和Sc(0,1,2,3mol;)铌酸锂晶体全息存储性能.通过晶体红外光谱测试发现:Sc:Fe:LiNbO3晶体中Sc的掺杂浓度超过3mol;时,Sc:Fe:LiNbO3晶体的O-H吸收峰的位置从低掺杂时的3484cm-1移动到3508cm-1.采用光斑畸变法测得(3mol;)Sc:Fe:LiNbO3晶体抗光损伤能力为3.3×103 W/cm2,比Fe:LiNbO3提高了二个数量级.晶体的红外吸收光谱和抗光损伤能力显示:Sc的掺杂浓度为3mol;时具有明显的阈值特征.采用波长为632nm的He-Ne激光器作为光源,通过二波耦合方法测试晶体全息存储性能.实验表明:在一系列Sc:Fe:LiNbO3晶体中,Sc(2mol;):Fe:LiNbO3晶体能获得最佳的光折变灵敏度和动态范围.     

In:Ce:Cu:LiNbO3晶体的生长及存储性能研究

在Ce∶Cu∶LiNbO3晶体中掺进In2O3,用CZ法首次生长In∶Ce∶Cu∶LiNbO3晶体.对晶体的抗光折变能力、红外光谱、指数增益系数、衍射效率和响应时间进行了测试,结果表明:In(3mol;)∶Ce∶Cu∶LiNbO3晶体的抗光折变能力比Ce∶Cu∶LiNbO3提高两个数量级,其OH-吸收峰由LiNbO3的3484 cm-1移到3508 cm-1,响应速度比Ce∶Cu∶LiNbO3晶体快三倍.对In∶Ce∶Cu∶LiNbO3晶体抗光折变能力提高的机理、红外光谱OH-吸收峰紫移的机理进行了研究.     

[Li]/[Nb]比对Ce:LiNbO3晶体结构及光折变性能的影响

在铌酸锂(LiNbO3,LN)中掺入摩尔分数为0.1;的CeO2,以提拉法从不同[Li]/[Nb]摩尔比([Li]/[Nb]=0.750,0.850,0.946,1.100)的熔体中生长出了Ce:LN晶体.测试了晶体的晶格常数、红外光谱和居里温度.结果表明:随着[Li]/[Nb]比的增加,晶体仍为三方的LN晶体,且晶格常数和晶胞体积没有发生大的变化,v(OH-)振动峰的位置依次向长波方向移动,居里温度依次增加,结构缺陷减少.由于Ce和[Li]/[Nb]比的协同作用,[Li]/[Nb]比为1.100的Ce:LN晶体已接近化学计量比,[Li]/[Nb]比为0.850的Ce:LN晶体的居里温度近似等于纯LN晶体.利用二波耦合光路测试了晶体的衍射效率、写入时间和擦除时间,计算了晶体的光折变灵敏度及动态范围.测试了晶体的抗光致散射能力,结果表明:[Li]/[Nb]比越高的Ce:LN晶体的光折变性能越好.并分析了不同[Li]/[Nb]比Ce:LN晶体光折变性能增强的机理.     

Cu:KNSBN晶体生长及其光折变效应的研究

在KNSBN晶体中掺进CuO,采用硅钼棒作加热体,以Czochralski技术生长Cu:KNSBN晶体.以二波耦合光路,测试晶体的衍射效率和记录时间,计算折射率变化值Δn.Cu:KNSBN晶体的衍射效率,记录速度和折射率变化值皆高于Fe:LiNbO3晶体.尤其记录速度比Fe:LiNbO3晶体高一个数量级以上.测试Cu:KNSBN晶体位相共轭反射率R和自泵浦位相共轭反射率RC.Cu:KNSBN晶体的自泵浦位相共轭反射率RC值达到64;,是纯KNSBN晶体的二倍.以Cu:KNSBN晶体自泵浦位相共轭镜进行消畸变实验.实验结果表明:输出光波确系输入探测光波的位相共轭光波.     

Optical damage resistance of Mg:Ce:Fe:LiNbO3 crystals

Mg:Ce:Fe:LiNbO₃ crystals were prepared with fixed concentrations of Fe₂O₃ and CeO₂, and differing concentrations of MgO by the Czochralski technique. Their infrared transmission spectra were measured in order to investigate their defect structures and their optical damage resistance was characterized by the photoinduced birefringence change and transmission facula distortion method. The optical damage resistance of Mg:Ce:Fe:LiNbO₃ crystals increases remarkably when the concentration of MgO exceeds a threshold concentration. The dependence of the optical damage resistance on the defect structure of Mg:Ce:Fe:LiNbO₃ crystals is discussed in detail. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Microstructure and optical properties of Zn:Mn:Fe:LiNbO3 crystals

Zn:Mn:Fe:LiNbO₃ crystals were prepared by Czochralski technique. Its microstructure was measured and analyzed by UV‐Vis absorption spectra. The optical damage resistance of Zn:Mn:Fe:LiNbO₃ crystals was characterized by the transmitted beam pattern distortion method. It increases remarkably when the concentration of ZnO is over a threshold concentration. Its value in Zn(7.0 mol%):Mn:Fe:LiNbO₃ crystal is about three orders of magnitude higher that in the Mn:Fe:LiNbO₃ crystal. The dependence of the defects on the optical damage resistance was discussed. The non‐volatile holographic storage was realized in all crystals, and the sensitivity of the Zn(7.0 mol%):Mn:Fe:LiNbO₃ crystal is much higher than that of others. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Scx:Fey:Cuz:LN晶体的生长及非挥发性全息存储的研究

本文首次采用Czochralski法生长优质的Scx:Fey:Cuz:LN (x=0,1;, 2;, 3;, 3.5;, y=0.1;, z=0.06;)晶体.测试了晶体抗光致散射能力,以二波耦合光路测试晶体的衍射效率、写入时间和擦除时间,计算光折变灵敏度和动态范围.结果表明:Sc(2mol;):Fe:Cu:LN和Sc(3mol;):Fe:Cu:LN晶体抗光致散射能力比Fe:Cu:LN晶体高两个数量级以上,Scx:Fey:Cuz:LN晶体的写入速度、光折变灵敏度和动态范围等全息存储性能优于Fe:LN晶体.首次采用氪离子激光(482.0 nm,蓝光)作开关光,氦氖激光(632.8 nm,红光)做记录光,以Sc:Fe:Cu:LN晶体作为双光子全息存储记录介质,实现了双光子全息存储固定(非挥发性全息存储).     

Structure and optical damage resistance of In:Yb:Er:LiNbO3 crystals

A series of In:Yb:Er:LiNbO₃ crystals have been grown. The UV‐Vis absorption spectra and Infrared (IR) transmission spectra were measured and discussed in terms of the spectroscopic characterizations and the defect structure of the In:Yb:Er:LiNbO₃ crystals. The optical damage resistance was characterized by the transmitted beam pattern distortion method. The optical damage resistance of In (3.0mol %):Yb:Er:LiNbO₃ crystal is one order of magnitude higher than that of other crystal. The dependence of the optical damage resistance on the defect structure was studied. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

In doping effect on optical properties in Zn:In:Fe:LiNbO3 crystals

A series of Zn:In:Fe:LiNbO₃ crystals were prepared by Czochralski method. The crystal composition and defect structure were analyzed by ICP‐OE/MS, UV–vis and IR spectroscopy. The results show that with increasing In³⁺ doping concentration in melt, the segregation coefficients of both Zn and In ions decrease. The optical damage resistance of Zn:In:Fe:LiNbO₃ crystals was studied by the transmitted beam pattern distortion method. It is found that the optical damage resistance of Zn:In(3mol%):Fe LiNbO₃ crystals is two orders of magnitude higher than that of Zn:Fe:LiNbO₃. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Defect structure and optical fixing holographic storage of Mg:Mn:Fe:LiNbO3 crystals

Mg:Mn:Fe:LiNbO₃ crystals were grown by the Czochralski method. The defect structure was analyzed by UV‐vis spectra and IR spectra. The holographic storage of Mg:Mn:Fe:LiNbO₃ crystals was measured by the two color fixed method. The results show that with the increase of MgO doping concentration, the writing time becomes shorter, the dynamic range decreases, photorefractive sensitivity increases and fixing diffraction efficiency decreases. When the MgO doping concentration exceeds 4.5 mol%, the fixing diffraction efficiency approaches zero. The effect of doping Mg ions on the holographic storage properties of Mn:Fe:LiNbO₃ crystals is discussed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Mg:In:Er:LiNbO3晶体生长及波导基片光损伤的研究

在LiNbO3中掺进MgO,In2O3,Er2O3以Czochralski技术系统生长了Mg(3mol;):In(1mol;):Er(1mol;):LiNbO3,Mg(3mol;):In(2mol;):Er(1mol;):LiNbO3,Mg(3mol;):In(3mol;):Er(1mol;):LiNbO3晶体.Mg(3mol;):In(3mol;):Er(1mol;):LiNbO3晶体荧光光谱表明4I13/2→ 4I15/2(1.53μm)易实现激光振荡.采用质子交换工艺制作Mg:In:Er:LiNbO3晶体波导基片并以m线法研究Mg:In:Er:LiNbO3晶体波导基片的光损伤.发现抗光损伤能力依次为:Mg:In(3mol;):Er:LiNbO3＞Mg:In(2mol;):Er:LiNbO3＞Mg:In(1mol;):Er:LiNbO3>Er:LiNbO3.以锂空位模型研究Mg:In:Er:LiNbO3晶体抗光损伤能力增强的机理.     

Characterization and luminescence of a-Si:H:Cl films

a-Si:H:Cl films have been deposited by glow-discharge and characterized by infrared transmission, optical absorption and photoluminescence. The influence of growth parameters on the H and Cl content has been investigated. The luminescence spectra show that three different radiative transitions can occur, at 0.75, 0.95 and ～1.3 eV. These bands have been interpreted respectively in terms of the following recombinations: defect to defect, defect to band tail, band tail to band tail.